Remove pg_collation.collversion.

This model couldn't be extended to cover the default collation, and
didn't have any information about the affected database objects when the
version changed.  Remove, in preparation for a follow-up commit that
will add a new mechanism.

Author: Thomas Munro <thomas.munro@gmail.com>
Reviewed-by: Julien Rouhaud <rjuju123@gmail.com>
Reviewed-by: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>
Discussion: https://postgr.es/m/CAEepm%3D0uEQCpfq_%2BLYFBdArCe4Ot98t1aR4eYiYTe%3DyavQygiQ%40mail.gmail.com

Author: macdice

doc/src/sgml/catalogs.sgml

@@ -2361,17 +2361,6 @@ SCRAM-SHA-256$<replaceable>&lt;iteration count&gt;</replaceable>:<replaceable>&l
        <symbol>LC_CTYPE</symbol> for this collation object
       </para></entry>
      </row>
-
-     <row>
-      <entry role="catalog_table_entry"><para role="column_definition">
-       <structfield>collversion</structfield> <type>text</type>
-      </para>
-      <para>
-       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.
-      </para></entry>
-     </row>
     </tbody>
    </tgroup>
   </table>

doc/src/sgml/func.sgml

@@ -25444,11 +25444,7 @@ postgres=# SELECT * FROM pg_walfile_name_offset(pg_stop_backup());
        </para>
        <para>
         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
-        <structname>pg_collation</structname>.<structfield>collversion</structfield>,
-        then objects depending on the collation might need to be rebuilt.  See
-        also <xref linkend="sql-altercollation"/>.
+        installed in the operating system.
        </para></entry>
       </row>
 

doc/src/sgml/ref/alter_collation.sgml

@@ -21,8 +21,6 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-ALTER COLLATION <replaceable>name</replaceable> REFRESH VERSION
-
 ALTER COLLATION <replaceable>name</replaceable> RENAME TO <replaceable>new_name</replaceable>
 ALTER COLLATION <replaceable>name</replaceable> OWNER TO { <replaceable>new_owner</replaceable> | CURRENT_ROLE | CURRENT_USER | SESSION_USER }
 ALTER COLLATION <replaceable>name</replaceable> SET SCHEMA <replaceable>new_schema</replaceable>
@@ -88,70 +86,9 @@ 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"/> below.
-     </para>
-    </listitem>
-   </varlistentry>
   </variablelist>
  </refsect1>
 
- <refsect1 id="sql-altercollation-notes" xreflabel="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>
 

doc/src/sgml/ref/create_collation.sgml

@@ -27,7 +27,6 @@ CREATE COLLATION [ IF NOT EXISTS ] <replaceable>name</replaceable> (
     [ LC_CTYPE = <replaceable>lc_ctype</replaceable>, ]
     [ PROVIDER = <replaceable>provider</replaceable>, ]
     [ DETERMINISTIC = <replaceable>boolean</replaceable>, ]
-    [ VERSION = <replaceable>version</replaceable> ]
 )
 CREATE COLLATION [ IF NOT EXISTS ] <replaceable>name</replaceable> FROM <replaceable>existing_collation</replaceable>
 </synopsis>
@@ -149,26 +148,6 @@ CREATE COLLATION [ IF NOT EXISTS ] <replaceable>name</replaceable> FROM <replace
      </listitem>
     </varlistentry>
 
-    <varlistentry>
-     <term><replaceable>version</replaceable></term>
-
-     <listitem>
-      <para>
-       Specifies the version string to store with the collation.  Normally,
-       this should be omitted, which will cause the version to be computed
-       from the actual version of the collation as provided by the operating
-       system.  This option is intended to be used
-       by <command>pg_upgrade</command> for copying the version from an
-       existing installation.
-      </para>
-
-      <para>
-       See also <xref linkend="sql-altercollation"/> for how to handle
-       collation version mismatches.
-      </para>
-     </listitem>
-    </varlistentry>
-
     <varlistentry>
      <term><replaceable>existing_collation</replaceable></term>
 

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);
 

src/backend/commands/collationcmds.c

@@ -61,14 +61,12 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 	DefElem    *lcctypeEl = NULL;
 	DefElem    *providerEl = NULL;
 	DefElem    *deterministicEl = NULL;
-	DefElem    *versionEl = NULL;
 	char	   *collcollate = NULL;
 	char	   *collctype = NULL;
 	char	   *collproviderstr = NULL;
 	bool		collisdeterministic = true;
 	int			collencoding = 0;
 	char		collprovider = 0;
-	char	   *collversion = NULL;
 	Oid			newoid;
 	ObjectAddress address;
 
@@ -96,8 +94,6 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 			defelp = &providerEl;
 		else if (strcmp(defel->defname, "deterministic") == 0)
 			defelp = &deterministicEl;
-		else if (strcmp(defel->defname, "version") == 0)
-			defelp = &versionEl;
 		else
 		{
 			ereport(ERROR,
@@ -166,9 +162,6 @@ 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)
@@ -215,9 +208,6 @@ 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(),
@@ -226,7 +216,6 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 							 collencoding,
 							 collcollate,
 							 collctype,
-							 collversion,
 							 if_not_exists,
 							 false);	/* not quiet */
 
@@ -277,80 +266,6 @@ 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)
 {
@@ -608,7 +523,6 @@ 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))
 			{
@@ -669,7 +583,6 @@ 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))
 			{
@@ -731,7 +644,6 @@ 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))
 			{

src/backend/nodes/copyfuncs.c

@@ -3224,16 +3224,6 @@ _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)
 {
@@ -5229,9 +5219,6 @@ 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;

src/backend/nodes/equalfuncs.c

@@ -1107,14 +1107,6 @@ _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)
 {
@@ -3283,9 +3275,6 @@ 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;