Remove 'datlastsysoid'.

It hasn't been used for anything for a long time. Up until recently,
we still queried it when dumping very old servers, but since
commit 30e7c175b81d53c0f60f6ad12d1913a6d7d77008, there's no longer any
code at all that cares about it.

Discussion: http://postgr.es/m/CA+Tgmoa14=BRq0WEd0eevjEMn9EkghDB1FZEkBw7+UAb7tF49A@mail.gmail.com

doc/src/sgml/bki.sgml

@@ -183,7 +183,7 @@
   descr => 'database\'s default template',
   datname => 'template1', encoding => 'ENCODING', datcollate => 'LC_COLLATE',
   datctype => 'LC_CTYPE', datistemplate => 't', datallowconn => 't',
-  datconnlimit => '-1', datlastsysoid => '0', datfrozenxid => '0',
+  datconnlimit => '-1', datfrozenxid => '0',
   datminmxid => '1', dattablespace => 'pg_default', datacl => '_null_' },
 
 ]

doc/src/sgml/catalogs.sgml

@@ -3001,16 +3001,6 @@ SCRAM-SHA-256$<replaceable>&lt;iteration count&gt;</replaceable>:<replaceable>&l
       </para></entry>
      </row>
 
-     <row>
-      <entry role="catalog_table_entry"><para role="column_definition">
-       <structfield>datlastsysoid</structfield> <type>oid</type>
-      </para>
-      <para>
-       Last system OID in the database; useful
-       particularly to <application>pg_dump</application>
-      </para></entry>
-     </row>
-
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
        <structfield>datfrozenxid</structfield> <type>xid</type>

doc/src/sgml/ecpg.sgml

@@ -4732,7 +4732,6 @@ encoding = 0 (type: 5)
 datistemplate = t (type: 1)
 datallowconn = t (type: 1)
 datconnlimit = -1 (type: 5)
-datlastsysoid = 11510 (type: 1)
 datfrozenxid = 379 (type: 1)
 dattablespace = 1663 (type: 1)
 datconfig =  (type: 1)
@@ -4757,7 +4756,6 @@ encoding = 0 (type: 5)
 datistemplate = f (type: 1)
 datallowconn = t (type: 1)
 datconnlimit = -1 (type: 5)
-datlastsysoid = 11510 (type: 1)
 datfrozenxid = 379 (type: 1)
 dattablespace = 1663 (type: 1)
 datconfig =  (type: 1)

src/backend/commands/dbcommands.c

@@ -84,8 +84,7 @@ static void movedb_failure_callback(int code, Datum arg);
 static bool get_db_info(const char *name, LOCKMODE lockmode,
 						Oid *dbIdP, Oid *ownerIdP,
 						int *encodingP, bool *dbIsTemplateP, bool *dbAllowConnP,
-						Oid *dbLastSysOidP, TransactionId *dbFrozenXidP,
+						TransactionId *dbFrozenXidP, MultiXactId *dbMinMultiP,
-						MultiXactId *dbMinMultiP,
 						Oid *dbTablespace, char **dbCollate, char **dbCtype);
 static bool have_createdb_privilege(void);
 static void remove_dbtablespaces(Oid db_id);
@@ -108,7 +107,6 @@ createdb(ParseState *pstate, const CreatedbStmt *stmt)
 	char	   *src_ctype = NULL;
 	bool		src_istemplate;
 	bool		src_allowconn;
-	Oid			src_lastsysoid = InvalidOid;
 	TransactionId src_frozenxid = InvalidTransactionId;
 	MultiXactId src_minmxid = InvalidMultiXactId;
 	Oid			src_deftablespace;
@@ -318,7 +316,7 @@ createdb(ParseState *pstate, const CreatedbStmt *stmt)
 
 	if (!get_db_info(dbtemplate, ShareLock,
 					 &src_dboid, &src_owner, &src_encoding,
-					 &src_istemplate, &src_allowconn, &src_lastsysoid,
+					 &src_istemplate, &src_allowconn,
 					 &src_frozenxid, &src_minmxid, &src_deftablespace,
 					 &src_collate, &src_ctype))
 		ereport(ERROR,
@@ -532,7 +530,6 @@ createdb(ParseState *pstate, const CreatedbStmt *stmt)
 	new_record[Anum_pg_database_datistemplate - 1] = BoolGetDatum(dbistemplate);
 	new_record[Anum_pg_database_datallowconn - 1] = BoolGetDatum(dballowconnections);
 	new_record[Anum_pg_database_datconnlimit - 1] = Int32GetDatum(dbconnlimit);
-	new_record[Anum_pg_database_datlastsysoid - 1] = ObjectIdGetDatum(src_lastsysoid);
 	new_record[Anum_pg_database_datfrozenxid - 1] = TransactionIdGetDatum(src_frozenxid);
 	new_record[Anum_pg_database_datminmxid - 1] = TransactionIdGetDatum(src_minmxid);
 	new_record[Anum_pg_database_dattablespace - 1] = ObjectIdGetDatum(dst_deftablespace);
@@ -802,7 +799,7 @@ dropdb(const char *dbname, bool missing_ok, bool force)
 	pgdbrel = table_open(DatabaseRelationId, RowExclusiveLock);
 
 	if (!get_db_info(dbname, AccessExclusiveLock, &db_id, NULL, NULL,
-					 &db_istemplate, NULL, NULL, NULL, NULL, NULL, NULL, NULL))
+					 &db_istemplate, NULL, NULL, NULL, NULL, NULL, NULL))
 	{
 		if (!missing_ok)
 		{
@@ -1001,7 +998,7 @@ RenameDatabase(const char *oldname, const char *newname)
 	rel = table_open(DatabaseRelationId, RowExclusiveLock);
 
 	if (!get_db_info(oldname, AccessExclusiveLock, &db_id, NULL, NULL,
-					 NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL))
+					 NULL, NULL, NULL, NULL, NULL, NULL, NULL))
 		ereport(ERROR,
 				(errcode(ERRCODE_UNDEFINED_DATABASE),
 				 errmsg("database \"%s\" does not exist", oldname)));
@@ -1114,7 +1111,7 @@ movedb(const char *dbname, const char *tblspcname)
 	pgdbrel = table_open(DatabaseRelationId, RowExclusiveLock);
 
 	if (!get_db_info(dbname, AccessExclusiveLock, &db_id, NULL, NULL,
-					 NULL, NULL, NULL, NULL, NULL, &src_tblspcoid, NULL, NULL))
+					 NULL, NULL, NULL, NULL, &src_tblspcoid, NULL, NULL))
 		ereport(ERROR,
 				(errcode(ERRCODE_UNDEFINED_DATABASE),
 				 errmsg("database \"%s\" does not exist", dbname)));
@@ -1757,8 +1754,7 @@ static bool
 get_db_info(const char *name, LOCKMODE lockmode,
 			Oid *dbIdP, Oid *ownerIdP,
 			int *encodingP, bool *dbIsTemplateP, bool *dbAllowConnP,
-			Oid *dbLastSysOidP, TransactionId *dbFrozenXidP,
+			TransactionId *dbFrozenXidP, MultiXactId *dbMinMultiP,
-			MultiXactId *dbMinMultiP,
 			Oid *dbTablespace, char **dbCollate, char **dbCtype)
 {
 	bool		result = false;
@@ -1839,9 +1835,6 @@ get_db_info(const char *name, LOCKMODE lockmode,
 				/* allowing connections? */
 				if (dbAllowConnP)
 					*dbAllowConnP = dbform->datallowconn;
-				/* last system OID used in database */
-				if (dbLastSysOidP)
-					*dbLastSysOidP = dbform->datlastsysoid;
 				/* limit of frozen XIDs */
 				if (dbFrozenXidP)
 					*dbFrozenXidP = dbform->datfrozenxid;

src/bin/initdb/initdb.c

@@ -1841,13 +1841,6 @@ make_template0(FILE *cmdfd)
 	static const char *const template0_setup[] = {
 		"CREATE DATABASE template0 IS_TEMPLATE = true ALLOW_CONNECTIONS = false;\n\n",
 
-		/*
-		 * We use the OID of template0 to determine datlastsysoid
-		 */
-		"UPDATE pg_database SET datlastsysoid = "
-		"    (SELECT oid FROM pg_database "
-		"    WHERE datname = 'template0');\n\n",
-
 		/*
 		 * Explicitly revoke public create-schema and create-temp-table
 		 * privileges in template1 and template0; else the latter would be on

src/include/catalog/catversion.h

@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	202201191
+#define CATALOG_VERSION_NO	202201201
 
 #endif

src/include/catalog/pg_database.dat

@@ -16,7 +16,7 @@
   descr => 'default template for new databases',
   datname => 'template1', encoding => 'ENCODING', datcollate => 'LC_COLLATE',
   datctype => 'LC_CTYPE', datistemplate => 't', datallowconn => 't',
-  datconnlimit => '-1', datlastsysoid => '0', datfrozenxid => '0',
+  datconnlimit => '-1', datfrozenxid => '0',
   datminmxid => '1', dattablespace => 'pg_default', datacl => '_null_' },
 
 ]

src/include/catalog/pg_database.h

@@ -55,9 +55,6 @@ CATALOG(pg_database,1262,DatabaseRelationId) BKI_SHARED_RELATION BKI_ROWTYPE_OID
 	/* max connections allowed (-1=no limit) */
 	int32		datconnlimit;
 
-	/* highest OID to consider a system OID */
-	Oid			datlastsysoid;
-
 	/* all Xids < this are frozen in this DB */
 	TransactionId datfrozenxid;