Subject: [PATCH v24 07/10] Add support for PRESERVE

From: Dilip Kumar <[email-masked]>
Date: Wed, 10 Feb 2021 11:49:23 +0530

Now the compression method can be changed without forcing a table
rewrite, by including the old method in the PRESERVE list.  For
supporting this the column will maintain the dependency with all
the supported compression methods.  So whenever the compression
method is altered the dependency is added with the new compression
method and the dependency is removed for all the old compression
methods which are not given in the preserve list.  If PRESERVE ALL
is given then all the dependency is maintained.

Dilip Kumar based on the patches from Ildus Kurbangaliev.
Design input from Tomas Vondra and Robert Haas
Reviewed by Robert Haas, Tomas Vondra, Alexander Korotkov and Justin Pryzby
---
 doc/src/sgml/ref/alter_table.sgml           |  10 +-
 src/backend/catalog/pg_depend.c             |   7 +
 src/backend/commands/Makefile               |   1 +
 src/backend/commands/compressioncmds.c      | 300 ++++++++++++++++++++
 src/backend/commands/tablecmds.c            | 126 ++++----
 src/backend/executor/nodeModifyTable.c      |  12 +-
 src/backend/nodes/copyfuncs.c               |  17 +-
 src/backend/nodes/equalfuncs.c              |  15 +-
 src/backend/nodes/outfuncs.c                |  15 +-
 src/backend/parser/gram.y                   |  52 +++-
 src/backend/parser/parse_utilcmd.c          |   2 +-
 src/bin/pg_dump/pg_dump.c                   | 101 +++++++
 src/bin/pg_dump/pg_dump.h                   |  15 +-
 src/bin/psql/tab-complete.c                 |   7 +
 src/include/commands/defrem.h               |   7 +
 src/include/commands/tablecmds.h            |   2 +
 src/include/nodes/nodes.h                   |   1 +
 src/include/nodes/parsenodes.h              |  16 +-
 src/test/regress/expected/compression.out   |  37 ++-
 src/test/regress/expected/compression_1.out |  39 ++-
 src/test/regress/expected/create_index.out  |  56 ++--
 src/test/regress/sql/compression.sql        |   9 +
 22 files changed, 739 insertions(+), 108 deletions(-)
 create mode 100644 src/backend/commands/compressioncmds.c

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 0bd0c1a503..c9f443a59c 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -54,7 +54,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
-    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable> [ PRESERVE (<replaceable class="parameter">compression_preserve_list</replaceable>) | PRESERVE ALL ]
     ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
     ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -387,7 +387,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
 
    <varlistentry>
     <term>
-     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable></literal>
+     <literal>SET COMPRESSION <replaceable class="parameter">compression_method</replaceable> [ PRESERVE (<replaceable class="parameter">compression_preserve_list</replaceable>) | PRESERVE ALL ]</literal>
     </term>
     <listitem>
      <para>
@@ -395,6 +395,12 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
       methods are <literal>pglz</literal> and <literal>lz4</literal>.
       <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
       was used when building <productname>PostgreSQL</productname>.
+      The <literal>PRESERVE</literal> list contains a list of compression
+      methods used in the column and determines which of them may be kept.
+      Without <literal>PRESERVE</literal> or if any of the pre-existing
+      compression methods are not preserved, the table will be rewritten.  If
+      <literal>PRESERVE ALL</literal> is specified, then all of the existing
+      methods will be preserved and the table will not be rewritten.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/catalog/pg_depend.c b/src/backend/catalog/pg_depend.c
index 63da24322d..dd376484b7 100644
--- a/src/backend/catalog/pg_depend.c
+++ b/src/backend/catalog/pg_depend.c
@@ -17,6 +17,7 @@
 #include "access/genam.h"
 #include "access/htup_details.h"
 #include "access/table.h"
+#include "catalog/pg_am.h"
 #include "catalog/dependency.h"
 #include "catalog/indexing.h"
 #include "catalog/pg_collation.h"
@@ -125,6 +126,12 @@ recordMultipleDependencies(const ObjectAddress *depender,
 				if (referenced->objectId == DEFAULT_COLLATION_OID)
 					ignore_systempin = true;
 			}
+			/*
+			 * Record the dependency on compression access method for handling
+			 * preserve.
+			 */
+			if (referenced->classId == AccessMethodRelationId)
+				ignore_systempin = true;
 		}
 		else
 			Assert(!version);
diff --git a/src/backend/commands/Makefile b/src/backend/commands/Makefile
index e8504f0ae4..a7395ad77d 100644
--- a/src/backend/commands/Makefile
+++ b/src/backend/commands/Makefile
@@ -21,6 +21,7 @@ OBJS = \
 	cluster.o \
 	collationcmds.o \
 	comment.o \
+	compressioncmds.o \
 	constraint.o \
 	conversioncmds.o \
 	copy.o \
diff --git a/src/backend/commands/compressioncmds.c b/src/backend/commands/compressioncmds.c
new file mode 100644
index 0000000000..fd6db24e7f
--- /dev/null
+++ b/src/backend/commands/compressioncmds.c
@@ -0,0 +1,300 @@
+/*-------------------------------------------------------------------------
+ *
+ * compressioncmds.c
+ *	  Routines for SQL commands for attribute compression methods
+ *
+ * Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/backend/commands/compressioncmds.c
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/compressamapi.h"
+#include "access/heapam.h"
+#include "access/htup_details.h"
+#include "access/reloptions.h"
+#include "catalog/catalog.h"
+#include "catalog/dependency.h"
+#include "catalog/indexing.h"
+#include "catalog/pg_attribute.h"
+#include "catalog/pg_depend.h"
+#include "commands/defrem.h"
+#include "commands/tablecmds.h"
+#include "miscadmin.h"
+#include "nodes/parsenodes.h"
+#include "utils/builtins.h"
+#include "utils/fmgroids.h"
+#include "utils/lsyscache.h"
+
+/*
+ * Get list of all supported compression methods for the given attribute.
+ *
+ * We maintain dependency of the attribute on the pg_am row for the current
+ * compression AM and all the preserved compression AM.  So scan pg_depend and
+ * find the column dependency on the pg_am.  Collect the list of access method
+ * oids on which this attribute has a dependency.
+ */
+static List *
+lookup_attribute_compression(Oid attrelid, AttrNumber attnum, List *oldcmoids)
+{
+	LOCKMODE	lock = AccessShareLock;
+	HeapTuple	tup;
+	Relation	rel;
+	SysScanDesc scan;
+	ScanKeyData key[3];
+	List	   *cmoids = NIL;
+
+	rel = table_open(DependRelationId, lock);
+
+	ScanKeyInit(&key[0],
+				Anum_pg_depend_classid,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(RelationRelationId));
+	ScanKeyInit(&key[1],
+				Anum_pg_depend_objid,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(attrelid));
+	ScanKeyInit(&key[2],
+				Anum_pg_depend_objsubid,
+				BTEqualStrategyNumber, F_INT4EQ,
+				Int32GetDatum((int32) attnum));
+
+	scan = systable_beginscan(rel, DependDependerIndexId, true,
+							  NULL, 3, key);
+
+	while (HeapTupleIsValid(tup = systable_getnext(scan)))
+	{
+		Form_pg_depend depform = (Form_pg_depend) GETSTRUCT(tup);
+
+		if (depform->refclassid == AccessMethodRelationId)
+			cmoids = list_append_unique_oid(cmoids, depform->refobjid);
+	}
+
+	systable_endscan(scan);
+	table_close(rel, lock);
+
+	return cmoids;
+}
+
+/*
+ * Remove the attribute dependency on the old compression methods
+ *
+ * Scan the pg_depend and search the attribute dependency on the pg_am.  Remove
+ * dependency on previous am which is not preserved.  The list of non-preserved
+ * AMs is given in cmoids.
+ */
+static void
+remove_old_dependencies(Oid attrelid, AttrNumber attnum, List *cmoids)
+{
+	LOCKMODE	lock = AccessShareLock;
+	HeapTuple	tup;
+	Relation	rel;
+	SysScanDesc scan;
+	ScanKeyData key[3];
+
+	rel = table_open(DependRelationId, lock);
+
+	ScanKeyInit(&key[0],
+				Anum_pg_depend_classid,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(RelationRelationId));
+	ScanKeyInit(&key[1],
+				Anum_pg_depend_objid,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(attrelid));
+	ScanKeyInit(&key[2],
+				Anum_pg_depend_objsubid,
+				BTEqualStrategyNumber, F_INT4EQ,
+				Int32GetDatum((int32) attnum));
+
+	scan = systable_beginscan(rel, DependDependerIndexId, true,
+							  NULL, 3, key);
+
+	while (HeapTupleIsValid(tup = systable_getnext(scan)))
+	{
+		Form_pg_depend depform = (Form_pg_depend) GETSTRUCT(tup);
+
+		if (list_member_oid(cmoids, depform->refobjid))
+		{
+			Assert(depform->refclassid == AccessMethodRelationId);
+			CatalogTupleDelete(rel, &tup->t_self);
+		}
+	}
+
+	systable_endscan(scan);
+	table_close(rel, lock);
+}
+
+/*
+ * Check whether the given compression method oid is supported by
+ * the target attribute.
+ */
+bool
+IsCompressionSupported(Form_pg_attribute att, Oid cmoid)
+{
+	List	   *cmoids = NIL;
+
+	/* Check whether it is same as the current compression oid */
+	if (cmoid == att->attcompression)
+		return true;
+
+	/* Check the oid in all preserved compresion methods */
+	cmoids = lookup_attribute_compression(att->attrelid, att->attnum, NULL);
+	if (list_member_oid(cmoids, cmoid))
+		return true;
+	else
+		return false;
+}
+
+/*
+ * In binary upgrade mode add the dependencies for all the preserved compression
+ * method.
+ */
+static void
+BinaryUpgradeAddPreserve(Form_pg_attribute att, List *preserve)
+{
+	ListCell   *cell;
+
+	foreach(cell, preserve)
+	{
+		char   *cmname_p = strVal(lfirst(cell));
+		Oid		cmoid_p = get_compression_am_oid(cmname_p, false);
+
+		add_column_compression_dependency(att->attrelid, att->attnum, cmoid_p);
+	}
+}
+
+/*
+ * Get the compression method oid based on the compression method name.  When
+ * compression is not specified returns default attribute compression.  It is
+ * possible case for CREATE TABLE and ADD COLUMN commands where COMPRESSION
+ * syntax is optional.
+ *
+ * For ALTER command, check all the supported compression methods for the
+ * attribute and if the preserve list is not passed or some of the old
+ * compression methods are not given in the preserved list then delete
+ * dependency from the old compression methods and force the table rewrite.
+ */
+Oid
+GetAttributeCompression(Form_pg_attribute att, ColumnCompression *compression,
+						bool *need_rewrite)
+{
+	Oid			cmoid;
+	char		typstorage = get_typstorage(att->atttypid);
+	ListCell   *cell;
+
+	/*
+	 * No compression for the plain/external storage, refer comments atop
+	 * attcompression parameter in pg_attribute.h
+	 */
+	if (!IsStorageCompressible(typstorage))
+	{
+		if (compression == NULL)
+			return InvalidOid;
+
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("column data type %s does not support compression",
+						format_type_be(att->atttypid))));
+	}
+
+	/* fallback to default compression if it's not specified */
+	if (compression == NULL)
+		return GetDefaultToastCompression();
+
+	cmoid = get_compression_am_oid(compression->cmname, false);
+
+#ifndef HAVE_LIBLZ4
+	if (cmoid == LZ4_COMPRESSION_AM_OID)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("not built with lz4 support")));
+#endif
+
+	/*
+	 * Determine if the column needs rewrite or not. Rewrite conditions: SET
+	 * COMPRESSION without PRESERVE - SET COMPRESSION with PRESERVE but not
+	 * with full list of previous access methods.
+	 */
+	if (need_rewrite != NULL)
+	{
+		List	   *previous_cmoids = NIL;
+
+		*need_rewrite = false;
+
+		/*
+		 * In binary upgrade mode, just create a dependency on all preserved
+		 * methods.
+		 */
+		if (IsBinaryUpgrade)
+		{
+			BinaryUpgradeAddPreserve(att, compression->preserve);
+			return cmoid;
+		}
+
+		/* If we have preserved all then rewrite is not required */
+		if (compression->preserve_all)
+			return cmoid;
+
+		previous_cmoids =
+			lookup_attribute_compression(att->attrelid, att->attnum, NULL);
+
+		foreach(cell, compression->preserve)
+		{
+			char   *cmname_p = strVal(lfirst(cell));
+			Oid		cmoid_p = get_compression_am_oid(cmname_p, false);
+
+			if (!list_member_oid(previous_cmoids, cmoid_p))
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+							errmsg("\"%s\" compression access method cannot be preserved", cmname_p)));
+
+			/*
+			 * Remove from previous list, also protect from duplicate
+			 * entries in the PRESERVE list
+			 */
+			previous_cmoids = list_delete_oid(previous_cmoids, cmoid_p);
+		}
+
+		/* delete the current cmoid from the list */
+		previous_cmoids = list_delete_oid(previous_cmoids, cmoid);
+
+		/*
+		 * If the list of previous Oids is not empty after deletions then
+		 * we need to rewrite tuples in the table.  Also remove the dependency
+		 * on the old compression methods which are no longer preserved.
+		 */
+		if (list_length(previous_cmoids) != 0)
+		{
+			remove_old_dependencies(att->attrelid, att->attnum,
+									previous_cmoids);
+			*need_rewrite = true;
+		}
+
+		/* Cleanup */
+		list_free(previous_cmoids);
+	}
+
+	return cmoid;
+}
+
+/*
+ * Construct ColumnCompression node from the compression method oid.
+ */
+ColumnCompression *
+MakeColumnCompression(Oid attcompression)
+{
+	ColumnCompression *node;
+
+	if (!OidIsValid(attcompression))
+		return NULL;
+
+	node = makeNode(ColumnCompression);
+	node->cmname = get_am_name(attcompression);
+
+	return node;
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 586a92f0c1..2a1841c353 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -530,7 +530,9 @@ static void ATExecEnableRowSecurity(Relation rel);
 static void ATExecDisableRowSecurity(Relation rel);
 static void ATExecForceNoForceRowSecurity(Relation rel, bool force_rls);
 static ObjectAddress ATExecSetCompression(AlteredTableInfo *tab, Relation rel,
-					 const char *column, Node *newValue, LOCKMODE lockmode);
+										  const char *column,
+										  ColumnCompression *compression,
+										  LOCKMODE lockmode);
 
 static void index_copy_data(Relation rel, RelFileNode newrnode);
 static const char *storage_name(char c);
@@ -562,7 +564,6 @@ static void refuseDupeIndexAttach(Relation parentIdx, Relation partIdx,
 static List *GetParentedForeignKeyRefs(Relation partition);
 static void ATDetachCheckNoForeignKeyRefs(Relation partition);
 static void ATExecAlterCollationRefreshVersion(Relation rel, List *coll);
-static Oid GetAttributeCompression(Form_pg_attribute att, char *compression);
 
 /* ----------------------------------------------------------------
  *		DefineRelation
@@ -587,6 +588,7 @@ ObjectAddress
 DefineRelation(CreateStmt *stmt, char relkind, Oid ownerId,
 			   ObjectAddress *typaddress, const char *queryString)
 {
+	int			i;
 	char		relname[NAMEDATALEN];
 	Oid			namespaceId;
 	Oid			relationId;
@@ -865,7 +867,7 @@ DefineRelation(CreateStmt *stmt, char relkind, Oid ownerId,
 			relkind == RELKIND_PARTITIONED_TABLE ||
 			relkind == RELKIND_MATVIEW)
 			attr->attcompression =
-				GetAttributeCompression(attr, colDef->compression);
+				GetAttributeCompression(attr, colDef->compression, NULL);
 		else
 			attr->attcompression = InvalidOid;
 	}
@@ -935,6 +937,20 @@ DefineRelation(CreateStmt *stmt, char relkind, Oid ownerId,
 	 */
 	rel = relation_open(relationId, AccessExclusiveLock);
 
+	/*
+	 * Add the dependency on the respective compression AM for the relation
+	 * attributes.
+	 */
+	for (i = 0; i < (RelationGetDescr(rel))->natts; i++)
+	{
+		Form_pg_attribute attr;
+
+		attr = TupleDescAttr(RelationGetDescr(rel), i);
+		if (OidIsValid(attr->attcompression))
+			add_column_compression_dependency(attr->attrelid, attr->attnum,
+											  attr->attcompression);
+	}
+
 	/*
 	 * Now add any newly specified column default and generation expressions
 	 * to the new relation.  These are passed to us in the form of raw
@@ -2415,16 +2431,17 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 				/* Copy/check compression parameter */
 				if (OidIsValid(attribute->attcompression))
 				{
-					char *compression = get_am_name(attribute->attcompression);
+					ColumnCompression *compression =
+							MakeColumnCompression(attribute->attcompression);
 
 					if (!def->compression)
 						def->compression = compression;
-					else if (strcmp(def->compression, compression) != 0)
+					else if (strcmp(def->compression->cmname, compression->cmname))
 						ereport(ERROR,
 								(errcode(ERRCODE_DATATYPE_MISMATCH),
 								 errmsg("column \"%s\" has a compression method conflict",
 										attributeName),
-								 errdetail("%s versus %s", def->compression, compression)));
+								 errdetail("%s versus %s", def->compression->cmname, compression->cmname)));
 				}
 
 				def->inhcount++;
@@ -2461,7 +2478,8 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 				def->collOid = attribute->attcollation;
 				def->constraints = NIL;
 				def->location = -1;
-				def->compression = get_am_name(attribute->attcompression);
+				def->compression = MakeColumnCompression(
+											attribute->attcompression);
 				inhSchema = lappend(inhSchema, def);
 				newattmap->attnums[parent_attno - 1] = ++child_attno;
 			}
@@ -2712,12 +2730,12 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 					def->compression = newdef->compression;
 				else if (newdef->compression)
 				{
-					if (strcmp(def->compression, newdef->compression))
+					if (strcmp(def->compression->cmname, newdef->compression->cmname))
 						ereport(ERROR,
 								(errcode(ERRCODE_DATATYPE_MISMATCH),
 								 errmsg("column \"%s\" has a compression method conflict",
 										attributeName),
-								 errdetail("%s versus %s", def->compression, newdef->compression)));
+								 errdetail("%s versus %s", def->compression->cmname, newdef->compression->cmname)));
 				}
 
 				/* Mark the column as locally defined */
@@ -4908,7 +4926,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			ATExecAlterCollationRefreshVersion(rel, cmd->object);
 			break;
 		case AT_SetCompression:
-			address = ATExecSetCompression(tab, rel, cmd->name, cmd->def,
+			address = ATExecSetCompression(tab, rel, cmd->name,
+										   (ColumnCompression *) cmd->def,
 										   lockmode);
 			break;
 		default:				/* oops */
@@ -6414,7 +6433,8 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
 	if (rel->rd_rel->relkind == RELKIND_RELATION ||
 		rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
 		attribute.attcompression = GetAttributeCompression(&attribute,
-														   colDef->compression);
+														   colDef->compression,
+														   NULL);
 	else
 		attribute.attcompression = InvalidOid;
 
@@ -6589,6 +6609,7 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
 	 */
 	add_column_datatype_dependency(myrelid, newattnum, attribute.atttypid);
 	add_column_collation_dependency(myrelid, newattnum, attribute.attcollation);
+	add_column_compression_dependency(myrelid, newattnum, attribute.attcompression);
 
 	/*
 	 * Propagate to children as appropriate.  Unlike most other ALTER
@@ -6736,6 +6757,28 @@ add_column_collation_dependency(Oid relid, int32 attnum, Oid collid)
 	}
 }
 
+/*
+ * Install a dependency for compression on its column.
+ *
+ * This is used for identifying all the supported compression methods
+ * (current and preserved) for a attribute.
+ *
+ * If dependency is already there the whole thing is skipped.
+ */
+void
+add_column_compression_dependency(Oid relid, int32 attnum, Oid cmoid)
+{
+	ObjectAddress acref,
+		attref;
+
+	Assert(relid > 0 && attnum > 0);
+
+	ObjectAddressSet(acref, AccessMethodRelationId, cmoid);
+	ObjectAddressSubSet(attref, RelationRelationId, relid, attnum);
+
+	recordMultipleDependencies(&attref, &acref, 1, DEPENDENCY_NORMAL, true);
+}
+
 /*
  * ALTER TABLE ALTER COLUMN DROP NOT NULL
  */
@@ -11867,7 +11910,8 @@ ATExecAlterColumnType(AlteredTableInfo *tab, Relation rel,
 			  foundDep->refobjid == attTup->attcollation) &&
 			!(foundDep->refclassid == RelationRelationId &&
 			  foundDep->refobjid == RelationGetRelid(rel) &&
-			  foundDep->refobjsubid != 0)
+			  foundDep->refobjsubid != 0) &&
+			  foundDep->refclassid != AccessMethodRelationId
 			)
 			elog(ERROR, "found unexpected dependency for column: %s",
 				 getObjectDescription(&foundObject, false));
@@ -11982,6 +12026,11 @@ ATExecAlterColumnType(AlteredTableInfo *tab, Relation rel,
 	add_column_datatype_dependency(RelationGetRelid(rel), attnum, targettype);
 	add_column_collation_dependency(RelationGetRelid(rel), attnum, targetcollid);
 
+	/* Create dependency for new attribute compression */
+	if (OidIsValid(attTup->attcompression))
+		add_column_compression_dependency(RelationGetRelid(rel), attnum,
+										  attTup->attcompression);
+
 	/*
 	 * Drop any pg_statistic entry for the column, since it's now wrong type
 	 */
@@ -15086,24 +15135,21 @@ static ObjectAddress
 ATExecSetCompression(AlteredTableInfo *tab,
 					 Relation rel,
 					 const char *column,
-					 Node *newValue,
+					 ColumnCompression *compression,
 					 LOCKMODE lockmode)
 {
 	Relation	attrel;
 	HeapTuple	tuple;
 	Form_pg_attribute atttableform;
 	AttrNumber	attnum;
-	char	   *compression;
 	char		typstorage;
 	Oid			cmoid;
+	bool		need_rewrite;
 	Datum		values[Natts_pg_attribute];
 	bool		nulls[Natts_pg_attribute];
 	bool		replace[Natts_pg_attribute];
 	ObjectAddress address;
 
-	Assert(IsA(newValue, String));
-	compression = strVal(newValue);
-
 	attrel = table_open(AttributeRelationId, RowExclusiveLock);
 
 	tuple = SearchSysCacheAttName(RelationGetRelid(rel), column);
@@ -15136,11 +15182,16 @@ ATExecSetCompression(AlteredTableInfo *tab,
 	memset(replace, false, sizeof(replace));
 
 	/* Get the attribute compression method. */
-	cmoid = GetAttributeCompression(atttableform, compression);
+	cmoid = GetAttributeCompression(atttableform, compression, &need_rewrite);
 
 	if (atttableform->attcompression != cmoid)
+		add_column_compression_dependency(atttableform->attrelid,
+										  atttableform->attnum, cmoid);
+	if (need_rewrite)
 		tab->rewrite |= AT_REWRITE_ALTER_COMPRESSION;
 
+	atttableform->attcompression = cmoid;
+
 	atttableform->attcompression = cmoid;
 	CatalogTupleUpdate(attrel, &tuple->t_self, tuple);
 
@@ -17865,42 +17916,3 @@ ATExecAlterCollationRefreshVersion(Relation rel, List *coll)
 	index_update_collation_versions(rel->rd_id, get_collation_oid(coll, false));
 	CacheInvalidateRelcache(rel);
 }
-
-/*
- * resolve column compression specification to an OID.
- */
-static Oid
-GetAttributeCompression(Form_pg_attribute att, char *compression)
-{
-	char		typstorage = get_typstorage(att->atttypid);
-	Oid			amoid;
-
-	/*
-	 * No compression for the plain/external storage, refer comments atop
-	 * attcompression parameter in pg_attribute.h
-	 */
-	if (!IsStorageCompressible(typstorage))
-	{
-		if (compression == NULL)
-			return InvalidOid;
-
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("column data type %s does not support compression",
-						format_type_be(att->atttypid))));
-	}
-
-	/* fallback to default compression if it's not specified */
-	if (compression == NULL)
-		return GetDefaultToastCompression();
-
-	amoid = get_compression_am_oid(compression, false);
-
-#ifndef HAVE_LIBLZ4
-	if (amoid == LZ4_COMPRESSION_AM_OID)
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("not built with lz4 support")));
-#endif
-	return amoid;
-}
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index ea82a05591..90d092671e 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -44,6 +44,7 @@
 #include "access/tableam.h"
 #include "access/xact.h"
 #include "catalog/catalog.h"
+#include "commands/defrem.h"
 #include "commands/trigger.h"
 #include "executor/execPartition.h"
 #include "executor/executor.h"
@@ -2068,8 +2069,8 @@ CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 
 	/*
 	 * Loop over all the attributes in the tuple and check if any attribute is
-	 * compressed and its compression method is not same as the target
-	 * atrribute's compression method then decompress it.
+	 * compressed and its compression method is not is not supported by the
+	 * target attribute then we need to decompress
 	 */
 	for (i = 0; i < natts; i++)
 	{
@@ -2094,12 +2095,13 @@ CompareCompressionMethodAndDecompress(TupleTableSlot *slot,
 				DatumGetPointer(slot->tts_values[attnum - 1]);
 
 			/*
-			 * Get the compression method Oid stored in the toast header and
-			 * compare it with the compression method of the target.
+			 * Get the compression method stored in the toast header and if the
+			 * compression method is not supported by the target attribute then
+			 * we need to decompress it.
 			 */
 			cmoid = toast_get_compression_oid(new_value);
 			if (OidIsValid(cmoid) &&
-				targetTupDesc->attrs[i].attcompression != cmoid)
+				!IsCompressionSupported(&targetTupDesc->attrs[i], cmoid))
 			{
 				new_value = detoast_attr(new_value);
 				slot->tts_values[attnum - 1] = PointerGetDatum(new_value);
diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index 1338e04409..6a11f8eb60 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -2966,7 +2966,7 @@ _copyColumnDef(const ColumnDef *from)
 
 	COPY_STRING_FIELD(colname);
 	COPY_NODE_FIELD(typeName);
-	COPY_STRING_FIELD(compression);
+	COPY_NODE_FIELD(compression);
 	COPY_SCALAR_FIELD(inhcount);
 	COPY_SCALAR_FIELD(is_local);
 	COPY_SCALAR_FIELD(is_not_null);
@@ -2986,6 +2986,18 @@ _copyColumnDef(const ColumnDef *from)
 	return newnode;
 }
 
+static ColumnCompression *
+_copyColumnCompression(const ColumnCompression *from)
+{
+	ColumnCompression *newnode = makeNode(ColumnCompression);
+
+	COPY_STRING_FIELD(cmname);
+	COPY_SCALAR_FIELD(preserve_all);
+	COPY_NODE_FIELD(preserve);
+
+	return newnode;
+}
+
 static Constraint *
 _copyConstraint(const Constraint *from)
 {
@@ -5675,6 +5687,9 @@ copyObjectImpl(const void *from)
 		case T_ColumnDef:
 			retval = _copyColumnDef(from);
 			break;
+		case T_ColumnCompression:
+			retval = _copyColumnCompression(from);
+			break;
 		case T_Constraint:
 			retval = _copyConstraint(from);
 			break;
diff --git a/src/backend/nodes/equalfuncs.c b/src/backend/nodes/equalfuncs.c
index f3592003da..26a9b85974 100644
--- a/src/backend/nodes/equalfuncs.c
+++ b/src/backend/nodes/equalfuncs.c
@@ -2599,7 +2599,7 @@ _equalColumnDef(const ColumnDef *a, const ColumnDef *b)
 {
 	COMPARE_STRING_FIELD(colname);
 	COMPARE_NODE_FIELD(typeName);
-	COMPARE_STRING_FIELD(compression);
+	COMPARE_NODE_FIELD(compression);
 	COMPARE_SCALAR_FIELD(inhcount);
 	COMPARE_SCALAR_FIELD(is_local);
 	COMPARE_SCALAR_FIELD(is_not_null);
@@ -2619,6 +2619,16 @@ _equalColumnDef(const ColumnDef *a, const ColumnDef *b)
 	return true;
 }
 
+static bool
+_equalColumnCompression(const ColumnCompression *a, const ColumnCompression *b)
+{
+	COMPARE_STRING_FIELD(cmname);
+	COMPARE_SCALAR_FIELD(preserve_all);
+	COMPARE_NODE_FIELD(preserve);
+
+	return true;
+}
+
 static bool
 _equalConstraint(const Constraint *a, const Constraint *b)
 {
@@ -3724,6 +3734,9 @@ equal(const void *a, const void *b)
 		case T_ColumnDef:
 			retval = _equalColumnDef(a, b);
 			break;
+		case T_ColumnCompression:
+			retval = _equalColumnCompression(a, b);
+			break;
 		case T_Constraint:
 			retval = _equalConstraint(a, b);
 			break;
diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index 0605ef3f84..b584a58ba3 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -2863,7 +2863,7 @@ _outColumnDef(StringInfo str, const ColumnDef *node)
 
 	WRITE_STRING_FIELD(colname);
 	WRITE_NODE_FIELD(typeName);
-	WRITE_STRING_FIELD(compression);
+	WRITE_NODE_FIELD(compression);
 	WRITE_INT_FIELD(inhcount);
 	WRITE_BOOL_FIELD(is_local);
 	WRITE_BOOL_FIELD(is_not_null);
@@ -2881,6 +2881,16 @@ _outColumnDef(StringInfo str, const ColumnDef *node)
 	WRITE_LOCATION_FIELD(location);
 }
 
+static void
+_outColumnCompression(StringInfo str, const ColumnCompression *node)
+{
+	WRITE_NODE_TYPE("COLUMNCOMPRESSION");
+
+	WRITE_STRING_FIELD(cmname);
+	WRITE_BOOL_FIELD(preserve_all);
+	WRITE_NODE_FIELD(preserve);
+}
+
 static void
 _outTypeName(StringInfo str, const TypeName *node)
 {
@@ -4258,6 +4268,9 @@ outNode(StringInfo str, const void *obj)
 			case T_ColumnDef:
 				_outColumnDef(str, obj);
 				break;
+			case T_ColumnCompression:
+				_outColumnCompression(str, obj);
+				break;
 			case T_TypeName:
 				_outTypeName(str, obj);
 				break;
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 30acfe615d..9eb2b04d58 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -596,7 +596,9 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 %type <list>		hash_partbound
 %type <defelt>		hash_partbound_elem
 
-%type <str>	optColumnCompression
+%type <node>	optColumnCompression alterColumnCompression
+%type <str>		compressionClause
+%type <list>	optCompressionPreserve
 
 /*
  * Non-keyword token types.  These are hard-wired into the "flex" lexer.
@@ -2309,12 +2311,12 @@ alter_table_cmd:
 					$$ = (Node *)n;
 				}
 			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET (COMPRESSION <cm>) */
-			| ALTER opt_column ColId SET optColumnCompression
+			| ALTER opt_column ColId SET alterColumnCompression
 				{
 					AlterTableCmd *n = makeNode(AlterTableCmd);
 					n->subtype = AT_SetCompression;
 					n->name = $3;
-					n->def = (Node *) makeString($5);
+					n->def = $5;
 					$$ = (Node *)n;
 				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
@@ -3437,7 +3439,7 @@ columnDef:	ColId Typename optColumnCompression create_generic_options ColQualLis
 					ColumnDef *n = makeNode(ColumnDef);
 					n->colname = $1;
 					n->typeName = $2;
-					n->compression = $3;
+					n->compression = (ColumnCompression *) $3;
 					n->inhcount = 0;
 					n->is_local = true;
 					n->is_not_null = false;
@@ -3492,13 +3494,43 @@ columnOptions:	ColId ColQualList
 				}
 		;
 
+optCompressionPreserve:
+			PRESERVE '(' name_list ')' { $$ = $3; }
+			| /*EMPTY*/ { $$ = NULL; }
+		;
+
+compressionClause:
+			COMPRESSION name { $$ = pstrdup($2); }
+		;
+
 optColumnCompression:
-					COMPRESSION name
-					{
-						$$ = $2;
-					}
-					| /*EMPTY*/	{ $$ = NULL; }
-				;
+			compressionClause
+				{
+					ColumnCompression *n = makeNode(ColumnCompression);
+					n->cmname = $1;
+					n->preserve = NIL;
+					$$ = (Node *) n;
+				}
+			| /*EMPTY*/	{ $$ = NULL; }
+		;
+
+alterColumnCompression:
+			compressionClause optCompressionPreserve
+				{
+					ColumnCompression *n = makeNode(ColumnCompression);
+					n->cmname = $1;
+					n->preserve = (List *) $2;
+					$$ = (Node *) n;
+				}
+			|	compressionClause PRESERVE ALL
+				{
+					ColumnCompression *n = makeNode(ColumnCompression);
+					n->cmname = $1;
+					n->preserve_all = true;
+					n->preserve = NIL;
+					$$ = (Node *) n;
+				}
+		;
 
 ColQualList:
 			ColQualList ColConstraint				{ $$ = lappend($1, $2); }
diff --git a/src/backend/parser/parse_utilcmd.c b/src/backend/parser/parse_utilcmd.c
index cf4413da64..45f4724a13 100644
--- a/src/backend/parser/parse_utilcmd.c
+++ b/src/backend/parser/parse_utilcmd.c
@@ -1086,7 +1086,7 @@ transformTableLikeClause(CreateStmtContext *cxt, TableLikeClause *table_like_cla
 		/* Likewise, copy compression if requested */
 		if ((table_like_clause->options & CREATE_TABLE_LIKE_COMPRESSION) != 0
 			&& OidIsValid(attribute->attcompression))
-			def->compression = get_am_name(attribute->attcompression);
+			def->compression = MakeColumnCompression(attribute->attcompression);
 		else
 			def->compression = NULL;
 
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index 46044cb92a..7bf345a4ac 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -9037,6 +9037,80 @@ getTableAttrs(Archive *fout, TableInfo *tblinfo, int numTables)
 			}
 			PQclear(res);
 		}
+
+		/*
+		 * Get compression info
+		 */
+		if (fout->remoteVersion >= 140000 && dopt->binary_upgrade)
+		{
+			int			i_amname;
+			int			i_amoid;
+			int			i_curattnum;
+			int			start;
+
+			pg_log_info("finding compression info for table \"%s.%s\"",
+						tbinfo->dobj.namespace->dobj.name,
+						tbinfo->dobj.name);
+
+			tbinfo->attcompression = pg_malloc0(tbinfo->numatts * sizeof(AttrCompressionInfo *));
+
+			resetPQExpBuffer(q);
+			appendPQExpBuffer(q,
+				" SELECT attrelid::pg_catalog.regclass AS relname, attname,"
+				" amname, am.oid as amoid, d.objsubid AS curattnum"
+				" FROM pg_depend d"
+				" JOIN pg_attribute a ON"
+				"	(classid = 'pg_class'::pg_catalog.regclass::pg_catalog.oid AND a.attrelid = d.objid"
+				"		AND a.attnum = d.objsubid AND d.deptype = 'n'"
+				"		AND d.refclassid = 'pg_am'::pg_catalog.regclass::pg_catalog.oid)"
+				" JOIN pg_am am ON"
+				"	(d.deptype = 'n' AND d.refobjid = am.oid)"
+				" WHERE (deptype = 'n' AND d.objid = %d AND a.attcompression != am.oid);",
+				tbinfo->dobj.catId.oid);
+
+			res = ExecuteSqlQuery(fout, q->data, PGRES_TUPLES_OK);
+			ntups = PQntuples(res);
+
+			if (ntups > 0)
+			{
+				int		j;
+				int		k;
+
+				i_amname = PQfnumber(res, "amname");
+				i_amoid = PQfnumber(res, "amoid");
+				i_curattnum = PQfnumber(res, "curattnum");
+
+				start = 0;
+
+				for (j = 0; j < ntups; j++)
+				{
+					int		attnum = atoi(PQgetvalue(res, j, i_curattnum));
+
+					if ((j == ntups - 1) || atoi(PQgetvalue(res, j + 1, i_curattnum)) != attnum)
+					{
+						AttrCompressionInfo *cminfo = pg_malloc(sizeof(AttrCompressionInfo));
+
+						cminfo->nitems = j - start + 1;
+						cminfo->items = pg_malloc(sizeof(AttrCompressionItem *) * cminfo->nitems);
+
+						for (k = start; k < start + cminfo->nitems; k++)
+						{
+							AttrCompressionItem	*cmitem = pg_malloc0(sizeof(AttrCompressionItem));
+
+							cmitem->amname = pg_strdup(PQgetvalue(res, k, i_amname));
+							cmitem->amoid = atooid(PQgetvalue(res, k, i_amoid));
+
+							cminfo->items[k - start] = cmitem;
+						}
+
+						tbinfo->attcompression[attnum - 1] = cminfo;
+						start = j + 1;	/* start from next */
+					}
+				}
+			}
+
+			PQclear(res);
+		}
 	}
 
 	destroyPQExpBuffer(q);
@@ -16343,6 +16417,33 @@ dumpTableSchema(Archive *fout, const TableInfo *tbinfo)
 								  qualrelname,
 								  fmtId(tbinfo->attnames[j]),
 								  tbinfo->attfdwoptions[j]);
+
+			/*
+			 * Dump per-column compression options
+			 */
+			if (tbinfo->attcompression && tbinfo->attcompression[j])
+			{
+				AttrCompressionInfo *cminfo = tbinfo->attcompression[j];
+
+				appendPQExpBuffer(q, "ALTER TABLE %s ALTER COLUMN %s\nSET COMPRESSION %s",
+									qualrelname, fmtId(tbinfo->attnames[j]), tbinfo->attcmnames[j]);
+
+				if (cminfo->nitems > 0)
+				{
+					appendPQExpBuffer(q, "\nPRESERVE (");
+					for (int i = 0; i < cminfo->nitems; i++)
+					{
+						AttrCompressionItem *item = cminfo->items[i];
+
+						if (i == 0)
+							appendPQExpBuffer(q, "%s", item->amname);
+						else
+							appendPQExpBuffer(q, ", %s", item->amname);
+					}
+					appendPQExpBuffer(q, ")");
+				}
+				appendPQExpBuffer(q, ";\n");
+			}
 		}
 
 		if (ftoptions)
diff --git a/src/bin/pg_dump/pg_dump.h b/src/bin/pg_dump/pg_dump.h
index 1789e18f46..a829528cd0 100644
--- a/src/bin/pg_dump/pg_dump.h
+++ b/src/bin/pg_dump/pg_dump.h
@@ -327,7 +327,8 @@ typedef struct _tableInfo
 	bool		needs_override; /* has GENERATED ALWAYS AS IDENTITY */
 	char	   *amname;			/* relation access method */
 	char	  **attcmnames;		/* per-attribute current compression method */
-
+	struct _attrCompressionInfo **attcompression; /* per-attribute all
+													 compression data */
 	/*
 	 * Stuff computed only for dumpable tables.
 	 */
@@ -356,6 +357,18 @@ typedef struct _attrDefInfo
 	bool		separate;		/* true if must dump as separate item */
 } AttrDefInfo;
 
+typedef struct _attrCompressionItem
+{
+	Oid			amoid;			/* attribute compression oid */
+	char	   *amname;			/* compression access method name */
+} AttrCompressionItem;
+
+typedef struct _attrCompressionInfo
+{
+	int			nitems;
+	AttrCompressionItem	**items;
+} AttrCompressionInfo;
+
 typedef struct _tableDataInfo
 {
 	DumpableObject dobj;
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index ffa8d05edf..869fd3676d 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2103,6 +2103,13 @@ psql_completion(const char *text, int start, int end)
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "(") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "("))
 		COMPLETE_WITH("n_distinct", "n_distinct_inherited");
+	/* ALTER TABLE ALTER [COLUMN] <foo> SET COMPRESSION */
+	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "COMPRESSION", MatchAny) ||
+			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "COMPRESSION", MatchAny))
+		COMPLETE_WITH("PRESERVE");
+	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "COMPRESSION", MatchAny, "PRESERVE") ||
+			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "COMPRESSION", MatchAny, "PRESERVE"))
+		COMPLETE_WITH("( ", "ALL");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET STORAGE */
 	else if (Matches("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET", "STORAGE") ||
 			 Matches("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET", "STORAGE"))
diff --git a/src/include/commands/defrem.h b/src/include/commands/defrem.h
index e5aea8a240..bd53f9bb0f 100644
--- a/src/include/commands/defrem.h
+++ b/src/include/commands/defrem.h
@@ -143,6 +143,13 @@ extern Oid	get_compression_am_oid(const char *amname, bool missing_ok);
 extern Oid	get_am_oid(const char *amname, bool missing_ok);
 extern char *get_am_name(Oid amOid);
 
+/* commands/compressioncmds.c */
+extern Oid GetAttributeCompression(Form_pg_attribute att,
+								   ColumnCompression *compression,
+								   bool *need_rewrite);
+extern ColumnCompression *MakeColumnCompression(Oid atttcompression);
+extern bool IsCompressionSupported(Form_pg_attribute att, Oid cmoid);
+
 /* support routines in commands/define.c */
 
 extern char *defGetString(DefElem *def);
diff --git a/src/include/commands/tablecmds.h b/src/include/commands/tablecmds.h
index b3d30acc35..e6c98e65d4 100644
--- a/src/include/commands/tablecmds.h
+++ b/src/include/commands/tablecmds.h
@@ -97,5 +97,7 @@ extern void RangeVarCallbackOwnsRelation(const RangeVar *relation,
 										 Oid relId, Oid oldRelId, void *arg);
 extern bool PartConstraintImpliedByRelConstraint(Relation scanrel,
 												 List *partConstraint);
+extern void add_column_compression_dependency(Oid relid, int32 attnum,
+											  Oid cmoid);
 
 #endif							/* TABLECMDS_H */
diff --git a/src/include/nodes/nodes.h b/src/include/nodes/nodes.h
index 20d6f96f62..24deaad253 100644
--- a/src/include/nodes/nodes.h
+++ b/src/include/nodes/nodes.h
@@ -481,6 +481,7 @@ typedef enum NodeTag
 	T_PartitionBoundSpec,
 	T_PartitionRangeDatum,
 	T_PartitionCmd,
+	T_ColumnCompression,
 	T_VacuumRelation,
 
 	/*
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index f9a87dee02..ce0913e18a 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -623,6 +623,20 @@ typedef struct RangeTableSample
 	int			location;		/* method name location, or -1 if unknown */
 } RangeTableSample;
 
+/*
+ * ColumnCompression - compression parameters for some attribute
+ *
+ * This represents compression information defined using clause:
+ * .. COMPRESSION <compression method> PRESERVE <compression methods>
+ */
+typedef struct ColumnCompression
+{
+	NodeTag		type;
+	char	   *cmname;
+	bool		preserve_all;
+	List	   *preserve;
+} ColumnCompression;
+
 /*
  * ColumnDef - column definition (used in various creates)
  *
@@ -646,7 +660,7 @@ typedef struct ColumnDef
 	NodeTag		type;
 	char	   *colname;		/* name of column */
 	TypeName   *typeName;		/* type of column */
-	char	   *compression;	/* compression method for column */
+	ColumnCompression *compression;	/* column compression */
 	int			inhcount;		/* number of times column is inherited */
 	bool		is_local;		/* column has local (non-inherited) def'n */
 	bool		is_not_null;	/* NOT NULL constraint specified? */
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 21c1b451d2..3ed33b6534 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -226,12 +226,47 @@ SELECT pg_column_compression(f1) FROM cmpart;
  lz4
 (2 rows)
 
+-- preserve old compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION pglz PRESERVE (lz4);
+INSERT INTO cmdata VALUES (repeat('1234567890',1004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+(2 rows)
+
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4 PRESERVE ALL;
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ lz4
+ pglz
+(2 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  10040
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
  length 
diff --git a/src/test/regress/expected/compression_1.out b/src/test/regress/expected/compression_1.out
index 64c5855bf7..36a5f8ba5e 100644
--- a/src/test/regress/expected/compression_1.out
+++ b/src/test/regress/expected/compression_1.out
@@ -205,12 +205,49 @@ SELECT pg_column_compression(f1) FROM cmpart;
 ERROR:  relation "cmpart" does not exist
 LINE 1: SELECT pg_column_compression(f1) FROM cmpart;
                                               ^
+-- preserve old compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION pglz PRESERVE (lz4);
+ERROR:  "lz4" compression access method cannot be preserved
+INSERT INTO cmdata VALUES (repeat('1234567890',1004));
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
+\d+ cmdata
+                                        Table "public.cmdata"
+ Column | Type | Collation | Nullable | Default | Storage  | Compression | Stats target | Description 
+--------+------+-----------+----------+---------+----------+-------------+--------------+-------------
+ f1     | text |           |          |         | extended | pglz        |              | 
+Indexes:
+    "idx" btree (f1)
+
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4 PRESERVE ALL;
+ERROR:  not built with lz4 support
+SELECT pg_column_compression(f1) FROM cmdata;
+ pg_column_compression 
+-----------------------
+ pglz
+ pglz
+(2 rows)
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
  length 
 --------
   10000
-(1 row)
+  10040
+(2 rows)
 
 SELECT length(f1) FROM cmdata1;
 ERROR:  relation "cmdata1" does not exist
diff --git a/src/test/regress/expected/create_index.out b/src/test/regress/expected/create_index.out
index 830fdddf24..8f984510ac 100644
--- a/src/test/regress/expected/create_index.out
+++ b/src/test/regress/expected/create_index.out
@@ -2066,19 +2066,21 @@ WHERE classid = 'pg_class'::regclass AND
 	    'concur_reindex_ind4'::regclass,
 	    'concur_reindex_matview'::regclass)
   ORDER BY 1, 2;
-                   obj                    |                           objref                           | deptype 
-------------------------------------------+------------------------------------------------------------+---------
- index concur_reindex_ind1                | constraint concur_reindex_ind1 on table concur_reindex_tab | i
- index concur_reindex_ind2                | collation "default"                                        | n
- index concur_reindex_ind2                | column c2 of table concur_reindex_tab                      | a
- index concur_reindex_ind3                | column c1 of table concur_reindex_tab                      | a
- index concur_reindex_ind3                | table concur_reindex_tab                                   | a
- index concur_reindex_ind4                | collation "default"                                        | n
- index concur_reindex_ind4                | column c1 of table concur_reindex_tab                      | a
- index concur_reindex_ind4                | column c2 of table concur_reindex_tab                      | a
- materialized view concur_reindex_matview | schema public                                              | n
- table concur_reindex_tab                 | schema public                                              | n
-(10 rows)
+                          obj                          |                           objref                           | deptype 
+-------------------------------------------------------+------------------------------------------------------------+---------
+ column c2 of materialized view concur_reindex_matview | access method pglz                                         | n
+ column c2 of table concur_reindex_tab                 | access method pglz                                         | n
+ index concur_reindex_ind1                             | constraint concur_reindex_ind1 on table concur_reindex_tab | i
+ index concur_reindex_ind2                             | collation "default"                                        | n
+ index concur_reindex_ind2                             | column c2 of table concur_reindex_tab                      | a
+ index concur_reindex_ind3                             | column c1 of table concur_reindex_tab                      | a
+ index concur_reindex_ind3                             | table concur_reindex_tab                                   | a
+ index concur_reindex_ind4                             | collation "default"                                        | n
+ index concur_reindex_ind4                             | column c1 of table concur_reindex_tab                      | a
+ index concur_reindex_ind4                             | column c2 of table concur_reindex_tab                      | a
+ materialized view concur_reindex_matview              | schema public                                              | n
+ table concur_reindex_tab                              | schema public                                              | n
+(12 rows)
 
 REINDEX INDEX CONCURRENTLY concur_reindex_ind1;
 REINDEX TABLE CONCURRENTLY concur_reindex_tab;
@@ -2095,19 +2097,21 @@ WHERE classid = 'pg_class'::regclass AND
 	    'concur_reindex_ind4'::regclass,
 	    'concur_reindex_matview'::regclass)
   ORDER BY 1, 2;
-                   obj                    |                           objref                           | deptype 
-------------------------------------------+------------------------------------------------------------+---------
- index concur_reindex_ind1                | constraint concur_reindex_ind1 on table concur_reindex_tab | i
- index concur_reindex_ind2                | collation "default"                                        | n
- index concur_reindex_ind2                | column c2 of table concur_reindex_tab                      | a
- index concur_reindex_ind3                | column c1 of table concur_reindex_tab                      | a
- index concur_reindex_ind3                | table concur_reindex_tab                                   | a
- index concur_reindex_ind4                | collation "default"                                        | n
- index concur_reindex_ind4                | column c1 of table concur_reindex_tab                      | a
- index concur_reindex_ind4                | column c2 of table concur_reindex_tab                      | a
- materialized view concur_reindex_matview | schema public                                              | n
- table concur_reindex_tab                 | schema public                                              | n
-(10 rows)
+                          obj                          |                           objref                           | deptype 
+-------------------------------------------------------+------------------------------------------------------------+---------
+ column c2 of materialized view concur_reindex_matview | access method pglz                                         | n
+ column c2 of table concur_reindex_tab                 | access method pglz                                         | n
+ index concur_reindex_ind1                             | constraint concur_reindex_ind1 on table concur_reindex_tab | i
+ index concur_reindex_ind2                             | collation "default"                                        | n
+ index concur_reindex_ind2                             | column c2 of table concur_reindex_tab                      | a
+ index concur_reindex_ind3                             | column c1 of table concur_reindex_tab                      | a
+ index concur_reindex_ind3                             | table concur_reindex_tab                                   | a
+ index concur_reindex_ind4                             | collation "default"                                        | n
+ index concur_reindex_ind4                             | column c1 of table concur_reindex_tab                      | a
+ index concur_reindex_ind4                             | column c2 of table concur_reindex_tab                      | a
+ materialized view concur_reindex_matview              | schema public                                              | n
+ table concur_reindex_tab                              | schema public                                              | n
+(12 rows)
 
 -- Check that comments are preserved
 CREATE TABLE testcomment (i int);
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index b9daa33b74..5774b55d82 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -96,6 +96,15 @@ ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz;
 ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4;
 SELECT pg_column_compression(f1) FROM cmpart;
 
+-- preserve old compression method
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION pglz PRESERVE (lz4);
+INSERT INTO cmdata VALUES (repeat('1234567890',1004));
+\d+ cmdata
+SELECT pg_column_compression(f1) FROM cmdata;
+\d+ cmdata
+ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4 PRESERVE ALL;
+SELECT pg_column_compression(f1) FROM cmdata;
+
 -- check data is ok
 SELECT length(f1) FROM cmdata;
 SELECT length(f1) FROM cmdata1;
-- 
2.17.0

--m51xatjYGsM+13rf
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 filename="v24-0008-Create-custom-compression-methods.patch"