Subject: [PATCH 1/6] Remove pg_collation.collversion.

From: Thomas Munro <[email-masked]>
Date: Tue, 28 May 2019 14:15:28 -0400

A later patch will add version tracking for individual database objects
that depend on collations.

Author: Thomas Munro
Reviewed-by:
Discussion: https://postgr.es/m/CAEepm%3D0uEQCpfq_%2BLYFBdArCe4Ot98t1aR4eYiYTe%3DyavQygiQ%40mail.gmail.com
---
 doc/src/sgml/catalogs.sgml                    | 11 ---
 doc/src/sgml/func.sgml                        |  5 +-
 doc/src/sgml/ref/alter_collation.sgml         | 63 --------------
 src/backend/catalog/pg_collation.c            |  5 --
 src/backend/commands/collationcmds.c          | 85 -------------------
 src/backend/nodes/copyfuncs.c                 | 13 ---
 src/backend/nodes/equalfuncs.c                | 11 ---
 src/backend/parser/gram.y                     | 18 +---
 src/backend/tcop/utility.c                    | 12 ---
 src/backend/utils/adt/pg_locale.c             | 37 --------
 src/bin/pg_dump/pg_dump.c                     |  8 +-
 src/include/catalog/pg_collation.dat          |  7 +-
 src/include/catalog/pg_collation.h            |  5 --
 src/include/catalog/toasting.h                |  1 -
 src/include/commands/collationcmds.h          |  1 -
 src/include/nodes/parsenodes.h                | 11 ---
 .../regress/expected/collate.icu.utf8.out     |  3 -
 src/test/regress/sql/collate.icu.utf8.sql     |  5 --
 18 files changed, 11 insertions(+), 290 deletions(-)

diff --git a/doc/src/sgml/catalogs.sgml b/doc/src/sgml/catalogs.sgml
index 34bc0d0526..c299501c7b 100644
--- a/doc/src/sgml/catalogs.sgml
+++ b/doc/src/sgml/catalogs.sgml
@@ -2122,17 +2122,6 @@ SCRAM-SHA-256$<replaceable>&lt;iteration count&gt;</replaceable>:<replaceable>&l
       <entry></entry>
       <entry><symbol>LC_CTYPE</symbol> for this collation object</entry>
      </row>
-
-     <row>
-      <entry><structfield>collversion</structfield></entry>
-      <entry><type>text</type></entry>
-      <entry></entry>
-      <entry>
-       Provider-specific version of the collation.  This is recorded when the
-       collation is created and then checked when it is used, to detect
-       changes in the collation definition that could lead to data corruption.
-      </entry>
-     </row>
     </tbody>
    </tgroup>
   </table>
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 323366feb6..b2d991ac7f 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -21115,10 +21115,7 @@ postgres=# SELECT * FROM pg_walfile_name_offset(pg_stop_backup());
    <para>
     <function>pg_collation_actual_version</function> returns the actual
     version of the collation object as it is currently installed in the
-    operating system.  If this is different from the value
-    in <literal>pg_collation.collversion</literal>, then objects depending on
-    the collation might need to be rebuilt.  See also
-    <xref linkend="sql-altercollation"/>.
+    operating system.
    </para>
 
    <para>
diff --git a/doc/src/sgml/ref/alter_collation.sgml b/doc/src/sgml/ref/alter_collation.sgml
index 4cfcb42251..4241ec9f5a 100644
--- a/doc/src/sgml/ref/alter_collation.sgml
+++ b/doc/src/sgml/ref/alter_collation.sgml
@@ -88,72 +88,9 @@ ALTER COLLATION <replaceable>name</replaceable> SET SCHEMA <replaceable>new_sche
     </listitem>
    </varlistentry>
 
-   <varlistentry>
-    <term><literal>REFRESH VERSION</literal></term>
-    <listitem>
-     <para>
-      Update the collation's version.
-      See <xref linkend="sql-altercollation-notes"
-      endterm="sql-altercollation-notes-title"/> below.
-     </para>
-    </listitem>
-   </varlistentry>
   </variablelist>
  </refsect1>
 
- <refsect1 id="sql-altercollation-notes">
-  <title id="sql-altercollation-notes-title">Notes</title>
-
-  <para>
-   When using collations provided by the ICU library, the ICU-specific version
-   of the collator is recorded in the system catalog when the collation object
-   is created.  When the collation is used, the current version is
-   checked against the recorded version, and a warning is issued when there is
-   a mismatch, for example:
-<screen>
-WARNING:  collation "xx-x-icu" has version mismatch
-DETAIL:  The collation in the database was created using version 1.2.3.4, but the operating system provides version 2.3.4.5.
-HINT:  Rebuild all objects affected by this collation and run ALTER COLLATION pg_catalog."xx-x-icu" REFRESH VERSION, or build PostgreSQL with the right library version.
-</screen>
-   A change in collation definitions can lead to corrupt indexes and other
-   problems because the database system relies on stored objects having a
-   certain sort order.  Generally, this should be avoided, but it can happen
-   in legitimate circumstances, such as when
-   using <command>pg_upgrade</command> to upgrade to server binaries linked
-   with a newer version of ICU.  When this happens, all objects depending on
-   the collation should be rebuilt, for example,
-   using <command>REINDEX</command>.  When that is done, the collation version
-   can be refreshed using the command <literal>ALTER COLLATION ... REFRESH
-   VERSION</literal>.  This will update the system catalog to record the
-   current collator version and will make the warning go away.  Note that this
-   does not actually check whether all affected objects have been rebuilt
-   correctly.
-  </para>
-  <para>
-   When using collations provided by <literal>libc</literal> and
-   <productname>PostgreSQL</productname> was built with the GNU C library, the
-   C library's version is used as a collation version.  Since collation
-   definitions typically change only with GNU C library releases, this provides
-   some defense against corruption, but it is not completely reliable.
-  </para>
-  <para>
-   Currently, there is no version tracking for the database default collation.
-  </para>
-
-  <para>
-   The following query can be used to identify all collations in the current
-   database that need to be refreshed and the objects that depend on them:
-<programlisting><![CDATA[
-SELECT pg_describe_object(refclassid, refobjid, refobjsubid) AS "Collation",
-       pg_describe_object(classid, objid, objsubid) AS "Object"
-  FROM pg_depend d JOIN pg_collation c
-       ON refclassid = 'pg_collation'::regclass AND refobjid = c.oid
-  WHERE c.collversion <> pg_collation_actual_version(c.oid)
-  ORDER BY 1, 2;
-]]></programlisting>
-  </para>
- </refsect1>
-
  <refsect1>
   <title>Examples</title>
 
diff --git a/src/backend/catalog/pg_collation.c b/src/backend/catalog/pg_collation.c
index 8559779a4f..c78192e34b 100644
--- a/src/backend/catalog/pg_collation.c
+++ b/src/backend/catalog/pg_collation.c
@@ -49,7 +49,6 @@ CollationCreate(const char *collname, Oid collnamespace,
 				bool collisdeterministic,
 				int32 collencoding,
 				const char *collcollate, const char *collctype,
-				const char *collversion,
 				bool if_not_exists,
 				bool quiet)
 {
@@ -167,10 +166,6 @@ CollationCreate(const char *collname, Oid collnamespace,
 	values[Anum_pg_collation_collcollate - 1] = NameGetDatum(&name_collate);
 	namestrcpy(&name_ctype, collctype);
 	values[Anum_pg_collation_collctype - 1] = NameGetDatum(&name_ctype);
-	if (collversion)
-		values[Anum_pg_collation_collversion - 1] = CStringGetTextDatum(collversion);
-	else
-		nulls[Anum_pg_collation_collversion - 1] = true;
 
 	tup = heap_form_tuple(tupDesc, values, nulls);
 
diff --git a/src/backend/commands/collationcmds.c b/src/backend/commands/collationcmds.c
index 85f726ae06..493aa21a14 100644
--- a/src/backend/commands/collationcmds.c
+++ b/src/backend/commands/collationcmds.c
@@ -67,7 +67,6 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 	bool		collisdeterministic = true;
 	int			collencoding = 0;
 	char		collprovider = 0;
-	char	   *collversion = NULL;
 	Oid			newoid;
 	ObjectAddress address;
 
@@ -165,9 +164,6 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 	if (deterministicEl)
 		collisdeterministic = defGetBoolean(deterministicEl);
 
-	if (versionEl)
-		collversion = defGetString(versionEl);
-
 	if (collproviderstr)
 	{
 		if (pg_strcasecmp(collproviderstr, "icu") == 0)
@@ -214,9 +210,6 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 		}
 	}
 
-	if (!collversion)
-		collversion = get_collation_actual_version(collprovider, collcollate);
-
 	newoid = CollationCreate(collName,
 							 collNamespace,
 							 GetUserId(),
@@ -225,7 +218,6 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 							 collencoding,
 							 collcollate,
 							 collctype,
-							 collversion,
 							 if_not_exists,
 							 false);	/* not quiet */
 
@@ -276,80 +268,6 @@ IsThereCollationInNamespace(const char *collname, Oid nspOid)
 						collname, get_namespace_name(nspOid))));
 }
 
-/*
- * ALTER COLLATION
- */
-ObjectAddress
-AlterCollation(AlterCollationStmt *stmt)
-{
-	Relation	rel;
-	Oid			collOid;
-	HeapTuple	tup;
-	Form_pg_collation collForm;
-	Datum		collversion;
-	bool		isnull;
-	char	   *oldversion;
-	char	   *newversion;
-	ObjectAddress address;
-
-	rel = table_open(CollationRelationId, RowExclusiveLock);
-	collOid = get_collation_oid(stmt->collname, false);
-
-	if (!pg_collation_ownercheck(collOid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_COLLATION,
-					   NameListToString(stmt->collname));
-
-	tup = SearchSysCacheCopy1(COLLOID, ObjectIdGetDatum(collOid));
-	if (!HeapTupleIsValid(tup))
-		elog(ERROR, "cache lookup failed for collation %u", collOid);
-
-	collForm = (Form_pg_collation) GETSTRUCT(tup);
-	collversion = SysCacheGetAttr(COLLOID, tup, Anum_pg_collation_collversion,
-								  &isnull);
-	oldversion = isnull ? NULL : TextDatumGetCString(collversion);
-
-	newversion = get_collation_actual_version(collForm->collprovider, NameStr(collForm->collcollate));
-
-	/* cannot change from NULL to non-NULL or vice versa */
-	if ((!oldversion && newversion) || (oldversion && !newversion))
-		elog(ERROR, "invalid collation version change");
-	else if (oldversion && newversion && strcmp(newversion, oldversion) != 0)
-	{
-		bool		nulls[Natts_pg_collation];
-		bool		replaces[Natts_pg_collation];
-		Datum		values[Natts_pg_collation];
-
-		ereport(NOTICE,
-				(errmsg("changing version from %s to %s",
-						oldversion, newversion)));
-
-		memset(values, 0, sizeof(values));
-		memset(nulls, false, sizeof(nulls));
-		memset(replaces, false, sizeof(replaces));
-
-		values[Anum_pg_collation_collversion - 1] = CStringGetTextDatum(newversion);
-		replaces[Anum_pg_collation_collversion - 1] = true;
-
-		tup = heap_modify_tuple(tup, RelationGetDescr(rel),
-								values, nulls, replaces);
-	}
-	else
-		ereport(NOTICE,
-				(errmsg("version has not changed")));
-
-	CatalogTupleUpdate(rel, &tup->t_self, tup);
-
-	InvokeObjectPostAlterHook(CollationRelationId, collOid, 0);
-
-	ObjectAddressSet(address, CollationRelationId, collOid);
-
-	heap_freetuple(tup);
-	table_close(rel, NoLock);
-
-	return address;
-}
-
-
 Datum
 pg_collation_actual_version(PG_FUNCTION_ARGS)
 {
@@ -607,7 +525,6 @@ pg_import_system_collations(PG_FUNCTION_ARGS)
 			collid = CollationCreate(localebuf, nspid, GetUserId(),
 									 COLLPROVIDER_LIBC, true, enc,
 									 localebuf, localebuf,
-									 get_collation_actual_version(COLLPROVIDER_LIBC, localebuf),
 									 true, true);
 			if (OidIsValid(collid))
 			{
@@ -668,7 +585,6 @@ pg_import_system_collations(PG_FUNCTION_ARGS)
 			collid = CollationCreate(alias, nspid, GetUserId(),
 									 COLLPROVIDER_LIBC, true, enc,
 									 locale, locale,
-									 get_collation_actual_version(COLLPROVIDER_LIBC, locale),
 									 true, true);
 			if (OidIsValid(collid))
 			{
@@ -730,7 +646,6 @@ pg_import_system_collations(PG_FUNCTION_ARGS)
 									 nspid, GetUserId(),
 									 COLLPROVIDER_ICU, true, -1,
 									 collcollate, collcollate,
-									 get_collation_actual_version(COLLPROVIDER_ICU, collcollate),
 									 true, true);
 			if (OidIsValid(collid))
 			{
diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index e04c33e4ad..6a3b1b46e7 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -3184,16 +3184,6 @@ _copyAlterTableCmd(const AlterTableCmd *from)
 	return newnode;
 }
 
-static AlterCollationStmt *
-_copyAlterCollationStmt(const AlterCollationStmt *from)
-{
-	AlterCollationStmt *newnode = makeNode(AlterCollationStmt);
-
-	COPY_NODE_FIELD(collname);
-
-	return newnode;
-}
-
 static AlterDomainStmt *
 _copyAlterDomainStmt(const AlterDomainStmt *from)
 {
@@ -5173,9 +5163,6 @@ copyObjectImpl(const void *from)
 		case T_AlterTableCmd:
 			retval = _copyAlterTableCmd(from);
 			break;
-		case T_AlterCollationStmt:
-			retval = _copyAlterCollationStmt(from);
-			break;
 		case T_AlterDomainStmt:
 			retval = _copyAlterDomainStmt(from);
 			break;
diff --git a/src/backend/nodes/equalfuncs.c b/src/backend/nodes/equalfuncs.c
index 5b1ba143b1..4ec777a78c 100644
--- a/src/backend/nodes/equalfuncs.c
+++ b/src/backend/nodes/equalfuncs.c
@@ -1105,14 +1105,6 @@ _equalAlterTableCmd(const AlterTableCmd *a, const AlterTableCmd *b)
 	return true;
 }
 
-static bool
-_equalAlterCollationStmt(const AlterCollationStmt *a, const AlterCollationStmt *b)
-{
-	COMPARE_NODE_FIELD(collname);
-
-	return true;
-}
-
 static bool
 _equalAlterDomainStmt(const AlterDomainStmt *a, const AlterDomainStmt *b)
 {
@@ -3269,9 +3261,6 @@ equal(const void *a, const void *b)
 		case T_AlterTableCmd:
 			retval = _equalAlterTableCmd(a, b);
 			break;
-		case T_AlterCollationStmt:
-			retval = _equalAlterCollationStmt(a, b);
-			break;
 		case T_AlterDomainStmt:
 			retval = _equalAlterDomainStmt(a, b);
 			break;
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 96e7fdbcfe..d1ce351200 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -245,7 +245,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 }
 
 %type <node>	stmt schema_stmt
-		AlterEventTrigStmt AlterCollationStmt
+		AlterEventTrigStmt
 		AlterDatabaseStmt AlterDatabaseSetStmt AlterDomainStmt AlterEnumStmt
 		AlterFdwStmt AlterForeignServerStmt AlterGroupStmt
 		AlterObjectDependsStmt AlterObjectSchemaStmt AlterOwnerStmt
@@ -830,7 +830,6 @@ stmtmulti:	stmtmulti ';' stmt
 
 stmt :
 			AlterEventTrigStmt
-			| AlterCollationStmt
 			| AlterDatabaseStmt
 			| AlterDatabaseSetStmt
 			| AlterDefaultPrivilegesStmt
@@ -10324,21 +10323,6 @@ drop_option:
 				}
 		;
 
-/*****************************************************************************
- *
- *		ALTER COLLATION
- *
- *****************************************************************************/
-
-AlterCollationStmt: ALTER COLLATION any_name REFRESH VERSION_P
-				{
-					AlterCollationStmt *n = makeNode(AlterCollationStmt);
-					n->collname = $3;
-					$$ = (Node *)n;
-				}
-		;
-
-
 /*****************************************************************************
  *
  *		ALTER SYSTEM
diff --git a/src/backend/tcop/utility.c b/src/backend/tcop/utility.c
index 1b460a2612..21b04d5eb8 100644
--- a/src/backend/tcop/utility.c
+++ b/src/backend/tcop/utility.c
@@ -1788,10 +1788,6 @@ ProcessUtilitySlow(ParseState *pstate,
 				address = AlterStatistics((AlterStatsStmt *) parsetree);
 				break;
 
-			case T_AlterCollationStmt:
-				address = AlterCollation((AlterCollationStmt *) parsetree);
-				break;
-
 			default:
 				elog(ERROR, "unrecognized node type: %d",
 					 (int) nodeTag(parsetree));
@@ -2935,10 +2931,6 @@ CreateCommandTag(Node *parsetree)
 			tag = CMDTAG_DROP_SUBSCRIPTION;
 			break;
 
-		case T_AlterCollationStmt:
-			tag = CMDTAG_ALTER_COLLATION;
-			break;
-
 		case T_PrepareStmt:
 			tag = CMDTAG_PREPARE;
 			break;
@@ -3547,10 +3539,6 @@ GetCommandLogLevel(Node *parsetree)
 			lev = LOGSTMT_DDL;
 			break;
 
-		case T_AlterCollationStmt:
-			lev = LOGSTMT_DDL;
-			break;
-
 			/* already-planned queries */
 		case T_PlannedStmt:
 			{
diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index 64fd3ae18a..60dab33fcb 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -1352,8 +1352,6 @@ pg_newlocale_from_collation(Oid collid)
 		const char *collctype pg_attribute_unused();
 		struct pg_locale_struct result;
 		pg_locale_t resultp;
-		Datum		collversion;
-		bool		isnull;
 
 		tp = SearchSysCache1(COLLOID, ObjectIdGetDatum(collid));
 		if (!HeapTupleIsValid(tp))
@@ -1455,41 +1453,6 @@ pg_newlocale_from_collation(Oid collid)
 #endif							/* not USE_ICU */
 		}
 
-		collversion = SysCacheGetAttr(COLLOID, tp, Anum_pg_collation_collversion,
-									  &isnull);
-		if (!isnull)
-		{
-			char	   *actual_versionstr;
-			char	   *collversionstr;
-
-			actual_versionstr = get_collation_actual_version(collform->collprovider, collcollate);
-			if (!actual_versionstr)
-			{
-				/*
-				 * This could happen when specifying a version in CREATE
-				 * COLLATION for a libc locale, or manually creating a mess in
-				 * the catalogs.
-				 */
-				ereport(ERROR,
-						(errmsg("collation \"%s\" has no actual version, but a version was specified",
-								NameStr(collform->collname))));
-			}
-			collversionstr = TextDatumGetCString(collversion);
-
-			if (strcmp(actual_versionstr, collversionstr) != 0)
-				ereport(WARNING,
-						(errmsg("collation \"%s\" has version mismatch",
-								NameStr(collform->collname)),
-						 errdetail("The collation in the database was created using version %s, "
-								   "but the operating system provides version %s.",
-								   collversionstr, actual_versionstr),
-						 errhint("Rebuild all objects affected by this collation and run "
-								 "ALTER COLLATION %s REFRESH VERSION, "
-								 "or build PostgreSQL with the right library version.",
-								 quote_qualified_identifier(get_namespace_name(collform->collnamespace),
-															NameStr(collform->collname)))));
-		}
-
 		ReleaseSysCache(tp);
 
 		/* We'll keep the pg_locale_t structures in TopMemoryContext */
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index ef1539044f..81d6f3819a 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -13501,7 +13501,11 @@ dumpCollation(Archive *fout, CollInfo *collinfo)
 	/* Get collation-specific details */
 	appendPQExpBufferStr(query, "SELECT ");
 
-	if (fout->remoteVersion >= 100000)
+	if (fout->remoteVersion >= 130000)
+		appendPQExpBufferStr(query,
+							 "collprovider, "
+							 "NULL AS collversion, ");
+	else if (fout->remoteVersion >= 100000)
 		appendPQExpBufferStr(query,
 							 "collprovider, "
 							 "collversion, ");
@@ -13573,7 +13577,7 @@ dumpCollation(Archive *fout, CollInfo *collinfo)
 	 * For binary upgrade, carry over the collation version.  For normal
 	 * dump/restore, omit the version, so that it is computed upon restore.
 	 */
-	if (dopt->binary_upgrade)
+	if (dopt->binary_upgrade && fout->remoteVersion < 130000)
 	{
 		int			i_collversion;
 
diff --git a/src/include/catalog/pg_collation.dat b/src/include/catalog/pg_collation.dat
index ba1b3e201b..45301ccdd7 100644
--- a/src/include/catalog/pg_collation.dat
+++ b/src/include/catalog/pg_collation.dat
@@ -15,17 +15,16 @@
 { oid => '100', oid_symbol => 'DEFAULT_COLLATION_OID',
   descr => 'database\'s default collation',
   collname => 'default', collnamespace => 'PGNSP', collowner => 'PGUID',
-  collprovider => 'd', collencoding => '-1', collcollate => '', collctype => '',
-  collversion => '_null_' },
+  collprovider => 'd', collencoding => '-1', collcollate => '', collctype => '' },
 { oid => '950', oid_symbol => 'C_COLLATION_OID',
   descr => 'standard C collation',
   collname => 'C', collnamespace => 'PGNSP', collowner => 'PGUID',
   collprovider => 'c', collencoding => '-1', collcollate => 'C',
-  collctype => 'C', collversion => '_null_' },
+  collctype => 'C' },
 { oid => '951', oid_symbol => 'POSIX_COLLATION_OID',
   descr => 'standard POSIX collation',
   collname => 'POSIX', collnamespace => 'PGNSP', collowner => 'PGUID',
   collprovider => 'c', collencoding => '-1', collcollate => 'POSIX',
-  collctype => 'POSIX', collversion => '_null_' },
+  collctype => 'POSIX' },
 
 ]
diff --git a/src/include/catalog/pg_collation.h b/src/include/catalog/pg_collation.h
index 6955bb1273..cfde555366 100644
--- a/src/include/catalog/pg_collation.h
+++ b/src/include/catalog/pg_collation.h
@@ -37,10 +37,6 @@ CATALOG(pg_collation,3456,CollationRelationId)
 	int32		collencoding;	/* encoding for this collation; -1 = "all" */
 	NameData	collcollate;	/* LC_COLLATE setting */
 	NameData	collctype;		/* LC_CTYPE setting */
-#ifdef CATALOG_VARLEN			/* variable-length fields start here */
-	text		collversion;	/* provider-dependent version of collation
-								 * data */
-#endif
 } FormData_pg_collation;
 
 /* ----------------
@@ -65,7 +61,6 @@ extern Oid	CollationCreate(const char *collname, Oid collnamespace,
 							bool collisdeterministic,
 							int32 collencoding,
 							const char *collcollate, const char *collctype,
-							const char *collversion,
 							bool if_not_exists,
 							bool quiet);
 extern void RemoveCollationById(Oid collationOid);
diff --git a/src/include/catalog/toasting.h b/src/include/catalog/toasting.h
index 51491c4513..8f131893dc 100644
--- a/src/include/catalog/toasting.h
+++ b/src/include/catalog/toasting.h
@@ -51,7 +51,6 @@ extern void BootstrapToastTable(char *relName,
 /* normal catalogs */
 DECLARE_TOAST(pg_aggregate, 4159, 4160);
 DECLARE_TOAST(pg_attrdef, 2830, 2831);
-DECLARE_TOAST(pg_collation, 4161, 4162);
 DECLARE_TOAST(pg_constraint, 2832, 2833);
 DECLARE_TOAST(pg_default_acl, 4143, 4144);
 DECLARE_TOAST(pg_description, 2834, 2835);
diff --git a/src/include/commands/collationcmds.h b/src/include/commands/collationcmds.h
index df7d1d498c..9a9e145b4c 100644
--- a/src/include/commands/collationcmds.h
+++ b/src/include/commands/collationcmds.h
@@ -20,6 +20,5 @@
 
 extern ObjectAddress DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_exists);
 extern void IsThereCollationInNamespace(const char *collname, Oid nspOid);
-extern ObjectAddress AlterCollation(AlterCollationStmt *stmt);
 
 #endif							/* COLLATIONCMDS_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index da0706add5..c96d027362 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1870,17 +1870,6 @@ typedef struct AlterTableCmd	/* one subcommand of an ALTER TABLE */
 } AlterTableCmd;

-/* ----------------------
- * Alter Collation
- * ----------------------
- */
-typedef struct AlterCollationStmt
-{
-	NodeTag		type;
-	List	   *collname;
-} AlterCollationStmt;
-
-
 /* ----------------------
  *	Alter Domain
  *
diff --git a/src/test/regress/expected/collate.icu.utf8.out b/src/test/regress/expected/collate.icu.utf8.out
index 2b86ce9028..60d9263a2f 100644
--- a/src/test/regress/expected/collate.icu.utf8.out
+++ b/src/test/regress/expected/collate.icu.utf8.out
@@ -1082,9 +1082,6 @@ SELECT collname FROM pg_collation WHERE collname LIKE 'test%';
 
 DROP SCHEMA test_schema;
 DROP ROLE regress_test_role;
--- ALTER
-ALTER COLLATION "en-x-icu" REFRESH VERSION;
-NOTICE:  version has not changed
 -- dependencies
 CREATE COLLATION test0 FROM "C";
 CREATE TABLE collate_dep_test1 (a int, b text COLLATE test0);
diff --git a/src/test/regress/sql/collate.icu.utf8.sql b/src/test/regress/sql/collate.icu.utf8.sql
index 67de7d9794..35acf91fbf 100644
--- a/src/test/regress/sql/collate.icu.utf8.sql
+++ b/src/test/regress/sql/collate.icu.utf8.sql
@@ -405,11 +405,6 @@ DROP SCHEMA test_schema;
 DROP ROLE regress_test_role;

--- ALTER
-
-ALTER COLLATION "en-x-icu" REFRESH VERSION;
-
-
 -- dependencies
 
 CREATE COLLATION test0 FROM "C";
-- 
2.20.1

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