Clean up various to-do items associated with system indexes:

pg_database now has unique indexes on oid and on datname. pg_shadow now has unique indexes on usename and on usesysid. pg_am now has unique index on oid. pg_opclass now has unique index on oid. pg_amproc now has unique index on amid+amopclaid+amprocnum. Remove pg_rewrite's unnecessary index on oid, delete unused RULEOID syscache. Remove index on pg_listener and associated syscache for performance reasons (caching rows that are certain to change before you need 'em again is rather pointless). Change pg_attrdef's nonunique index on adrelid into a unique index on adrelid+adnum. Fix various incorrect settings of pg_class.relisshared, make that the primary reference point for whether a relation is shared or not. IsSharedSystemRelationName() is now only consulted to initialize relisshared during initial creation of tables and indexes. In theory we might now support shared user relations, though it's not clear how one would get entries for them into pg_class &etc of multiple databases. Fix recently reported bug that pg_attribute rows created for an index all have the same OID. (Proof that non-unique OID doesn't matter unless it's actually used to do lookups ;-)) There's no need to treat pg_trigger, pg_attrdef, pg_relcheck as bootstrap relations. Convert them into plain system catalogs without hardwired entries in pg_class and friends. Unify global.bki and template1.bki into a single init script postgres.bki, since the alleged distinction between them was misleading and pointless. Not to mention that it didn't work for setting up indexes on shared system relations. Rationalize locking of pg_shadow, pg_group, pg_attrdef (no need to use AccessExclusiveLock where ExclusiveLock or even RowExclusiveLock will do). Also, hold locks until transaction commit where necessary.
2025-11-07 19:06:32 +03:00 · 2001-06-12 05:55:50 +00:00
parent d2c8358188
commit 1d584f97b9
30 changed files with 471 additions and 647 deletions
--- a/src/backend/commands/async.c
+++ b/src/backend/commands/async.c
@@ -7,7 +7,7 @@
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/commands/async.c,v 1.77 2001/03/22 03:59:21 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/commands/async.c,v 1.78 2001/06/12 05:55:49 tgl Exp $
 *
 *-------------------------------------------------------------------------
 */
@@ -80,7 +80,6 @@

 #include "access/heapam.h"
 #include "catalog/catname.h"
-#include "catalog/indexing.h"
 #include "catalog/pg_listener.h"
 #include "commands/async.h"
 #include "lib/dllist.h"
@@ -195,11 +194,12 @@ void
 Async_Listen(char *relname, int pid)
 {
 	Relation	lRel;
+	HeapScanDesc scan;
 	HeapTuple	tuple;
 	Datum		values[Natts_pg_listener];
 	char		nulls[Natts_pg_listener];
 	int			i;
-	TupleDesc	tupDesc;
+	bool		alreadyListener = false;

 	if (Trace_notify)
 		elog(DEBUG, "Async_Listen: %s", relname);
@@ -207,12 +207,23 @@ Async_Listen(char *relname, int pid)
 	lRel = heap_openr(ListenerRelationName, AccessExclusiveLock);

 	/* Detect whether we are already listening on this relname */
-	if (SearchSysCacheExists(LISTENREL,
-							 Int32GetDatum(pid),
-							 PointerGetDatum(relname),
-							 0, 0))
+	scan = heap_beginscan(lRel, 0, SnapshotNow, 0, (ScanKey) NULL);
+	while (HeapTupleIsValid(tuple = heap_getnext(scan, 0)))
+	{
+		Form_pg_listener listener = (Form_pg_listener) GETSTRUCT(tuple);
+
+		if (listener->listenerpid == pid &&
+			strncmp(NameStr(listener->relname), relname, NAMEDATALEN) == 0)
+		{
+			alreadyListener = true;
+			/* No need to scan the rest of the table */
+			break;
+		}
+	}
+	heap_endscan(scan);
+
+	if (alreadyListener)
 	{
-		/* No need to scan the rest of the table */
 		heap_close(lRel, AccessExclusiveLock);
 		elog(NOTICE, "Async_Listen: We are already listening on %s", relname);
 		return;
@@ -233,9 +244,10 @@ Async_Listen(char *relname, int pid)
 	values[i++] = (Datum) pid;
 	values[i++] = (Datum) 0;	/* no notifies pending */

-	tupDesc = lRel->rd_att;
-	tuple = heap_formtuple(tupDesc, values, nulls);
+	tuple = heap_formtuple(RelationGetDescr(lRel), values, nulls);
 	heap_insert(lRel, tuple);
+
+#ifdef NOT_USED					/* currently there are no indexes */
 	if (RelationGetForm(lRel)->relhasindex)
 	{
 		Relation	idescs[Num_pg_listener_indices];
@@ -244,6 +256,7 @@ Async_Listen(char *relname, int pid)
 		CatalogIndexInsert(idescs, Num_pg_listener_indices, lRel, tuple);
 		CatalogCloseIndices(Num_pg_listener_indices, idescs);
 	}
+#endif

 	heap_freetuple(tuple);

@@ -280,7 +293,8 @@ void
 Async_Unlisten(char *relname, int pid)
 {
 	Relation	lRel;
-	HeapTuple	lTuple;
+	HeapScanDesc scan;
+	HeapTuple	tuple;

 	/* Handle specially the `unlisten "*"' command */
 	if ((!relname) || (*relname == '\0') || (strcmp(relname, "*") == 0))
@@ -293,16 +307,26 @@ Async_Unlisten(char *relname, int pid)
 		elog(DEBUG, "Async_Unlisten %s", relname);

 	lRel = heap_openr(ListenerRelationName, AccessExclusiveLock);
-	/* Note we assume there can be only one matching tuple. */
-	lTuple = SearchSysCache(LISTENREL,
-							Int32GetDatum(pid),
-							PointerGetDatum(relname),
-							0, 0);
-	if (HeapTupleIsValid(lTuple))
+
+	scan = heap_beginscan(lRel, 0, SnapshotNow, 0, (ScanKey) NULL);
+	while (HeapTupleIsValid(tuple = heap_getnext(scan, 0)))
 	{
-		simple_heap_delete(lRel, &lTuple->t_self);
-		ReleaseSysCache(lTuple);
+		Form_pg_listener listener = (Form_pg_listener) GETSTRUCT(tuple);
+
+		if (listener->listenerpid == pid &&
+			strncmp(NameStr(listener->relname), relname, NAMEDATALEN) == 0)
+		{
+			/* Found the matching tuple, delete it */
+			simple_heap_delete(lRel, &tuple->t_self);
+			/*
+			 * We assume there can be only one match, so no need
+			 * to scan the rest of the table
+			 */
+			break;
+		}
 	}
+	heap_endscan(scan);
+
 	heap_close(lRel, AccessExclusiveLock);

 	/*
@@ -332,7 +356,7 @@ Async_UnlistenAll()
 {
 	Relation	lRel;
 	TupleDesc	tdesc;
-	HeapScanDesc sRel;
+	HeapScanDesc scan;
 	HeapTuple	lTuple;
 	ScanKeyData key[1];

@@ -347,12 +371,12 @@ Async_UnlistenAll()
 						   Anum_pg_listener_pid,
 						   F_INT4EQ,
 						   Int32GetDatum(MyProcPid));
-	sRel = heap_beginscan(lRel, 0, SnapshotNow, 1, key);
+	scan = heap_beginscan(lRel, 0, SnapshotNow, 1, key);

-	while (HeapTupleIsValid(lTuple = heap_getnext(sRel, 0)))
+	while (HeapTupleIsValid(lTuple = heap_getnext(scan, 0)))
 		simple_heap_delete(lRel, &lTuple->t_self);

-	heap_endscan(sRel);
+	heap_endscan(scan);
 	heap_close(lRel, AccessExclusiveLock);
 }

@@ -418,16 +442,12 @@ AtCommit_Notify()
 {
 	Relation	lRel;
 	TupleDesc	tdesc;
-	HeapScanDesc sRel;
+	HeapScanDesc scan;
 	HeapTuple	lTuple,
 				rTuple;
-	Datum		d,
-				value[Natts_pg_listener];
+	Datum		value[Natts_pg_listener];
 	char		repl[Natts_pg_listener],
 				nulls[Natts_pg_listener];
-	bool		isnull;
-	char	   *relname;
-	int32		listenerPID;

 	if (!pendingNotifies)
 		return;					/* no NOTIFY statements in this
@@ -446,10 +466,6 @@ AtCommit_Notify()
 	if (Trace_notify)
 		elog(DEBUG, "AtCommit_Notify");

-	lRel = heap_openr(ListenerRelationName, AccessExclusiveLock);
-	tdesc = RelationGetDescr(lRel);
-	sRel = heap_beginscan(lRel, 0, SnapshotNow, 0, (ScanKey) NULL);
-
 	/* preset data to update notify column to MyProcPid */
 	nulls[0] = nulls[1] = nulls[2] = ' ';
 	repl[0] = repl[1] = repl[2] = ' ';
@@ -457,83 +473,81 @@ AtCommit_Notify()
 	value[0] = value[1] = value[2] = (Datum) 0;
 	value[Anum_pg_listener_notify - 1] = Int32GetDatum(MyProcPid);

-	while (HeapTupleIsValid(lTuple = heap_getnext(sRel, 0)))
+	lRel = heap_openr(ListenerRelationName, AccessExclusiveLock);
+	tdesc = RelationGetDescr(lRel);
+	scan = heap_beginscan(lRel, 0, SnapshotNow, 0, (ScanKey) NULL);
+
+	while (HeapTupleIsValid(lTuple = heap_getnext(scan, 0)))
 	{
-		d = heap_getattr(lTuple, Anum_pg_listener_relname, tdesc, &isnull);
-		relname = (char *) DatumGetPointer(d);
+		Form_pg_listener listener = (Form_pg_listener) GETSTRUCT(lTuple);
+		char	   *relname = NameStr(listener->relname);
+		int32		listenerPID = listener->listenerpid;

-		if (AsyncExistsPendingNotify(relname))
+		if (! AsyncExistsPendingNotify(relname))
+			continue;
+
+		if (listenerPID == MyProcPid)
 		{
-			d = heap_getattr(lTuple, Anum_pg_listener_pid, tdesc, &isnull);
-			listenerPID = DatumGetInt32(d);
+			/*
+			 * Self-notify: no need to bother with table update.
+			 * Indeed, we *must not* clear the notification field in
+			 * this path, or we could lose an outside notify, which'd
+			 * be bad for applications that ignore self-notify messages.
+			 */

-			if (listenerPID == MyProcPid)
+			if (Trace_notify)
+				elog(DEBUG, "AtCommit_Notify: notifying self");
+
+			NotifyMyFrontEnd(relname, listenerPID);
+		}
+		else
+		{
+			if (Trace_notify)
+				elog(DEBUG, "AtCommit_Notify: notifying pid %d",
+					 listenerPID);
+
+			/*
+			 * If someone has already notified this listener, we don't
+			 * bother modifying the table, but we do still send a
+			 * SIGUSR2 signal, just in case that backend missed the
+			 * earlier signal for some reason.	It's OK to send the
+			 * signal first, because the other guy can't read
+			 * pg_listener until we unlock it.
+			 */
+			if (kill(listenerPID, SIGUSR2) < 0)
 			{
-
 				/*
-				 * Self-notify: no need to bother with table update.
-				 * Indeed, we *must not* clear the notification field in
-				 * this path, or we could lose an outside notify, which'd
-				 * be bad for applications that ignore self-notify
-				 * messages.
+				 * Get rid of pg_listener entry if it refers to a PID
+				 * that no longer exists.  Presumably, that backend
+				 * crashed without deleting its pg_listener entries.
+				 * This code used to only delete the entry if
+				 * errno==ESRCH, but as far as I can see we should
+				 * just do it for any failure (certainly at least for
+				 * EPERM too...)
 				 */
-
-				if (Trace_notify)
-					elog(DEBUG, "AtCommit_Notify: notifying self");
-
-				NotifyMyFrontEnd(relname, listenerPID);
+				simple_heap_delete(lRel, &lTuple->t_self);
 			}
-			else
+			else if (listener->notification == 0)
 			{
-				if (Trace_notify)
-					elog(DEBUG, "AtCommit_Notify: notifying pid %d", listenerPID);
+				rTuple = heap_modifytuple(lTuple, lRel,
+										  value, nulls, repl);
+				simple_heap_update(lRel, &lTuple->t_self, rTuple);

-				/*
-				 * If someone has already notified this listener, we don't
-				 * bother modifying the table, but we do still send a
-				 * SIGUSR2 signal, just in case that backend missed the
-				 * earlier signal for some reason.	It's OK to send the
-				 * signal first, because the other guy can't read
-				 * pg_listener until we unlock it.
-				 */
-				if (kill(listenerPID, SIGUSR2) < 0)
+#ifdef NOT_USED					/* currently there are no indexes */
+				if (RelationGetForm(lRel)->relhasindex)
 				{
+					Relation	idescs[Num_pg_listener_indices];

-					/*
-					 * Get rid of pg_listener entry if it refers to a PID
-					 * that no longer exists.  Presumably, that backend
-					 * crashed without deleting its pg_listener entries.
-					 * This code used to only delete the entry if
-					 * errno==ESRCH, but as far as I can see we should
-					 * just do it for any failure (certainly at least for
-					 * EPERM too...)
-					 */
-					simple_heap_delete(lRel, &lTuple->t_self);
-				}
-				else
-				{
-					d = heap_getattr(lTuple, Anum_pg_listener_notify,
-									 tdesc, &isnull);
-					if (DatumGetInt32(d) == 0)
-					{
-						rTuple = heap_modifytuple(lTuple, lRel,
-												  value, nulls, repl);
-						simple_heap_update(lRel, &lTuple->t_self, rTuple);
-						if (RelationGetForm(lRel)->relhasindex)
-						{
-							Relation	idescs[Num_pg_listener_indices];
-
-							CatalogOpenIndices(Num_pg_listener_indices, Name_pg_listener_indices, idescs);
-							CatalogIndexInsert(idescs, Num_pg_listener_indices, lRel, rTuple);
-							CatalogCloseIndices(Num_pg_listener_indices, idescs);
-						}
-					}
+					CatalogOpenIndices(Num_pg_listener_indices, Name_pg_listener_indices, idescs);
+					CatalogIndexInsert(idescs, Num_pg_listener_indices, lRel, rTuple);
+					CatalogCloseIndices(Num_pg_listener_indices, idescs);
 				}
+#endif
 			}
 		}
 	}

-	heap_endscan(sRel);
+	heap_endscan(scan);

 	/*
 	 * We do NOT release the lock on pg_listener here; we need to hold it
@@ -745,16 +759,12 @@ ProcessIncomingNotify(void)
 	Relation	lRel;
 	TupleDesc	tdesc;
 	ScanKeyData key[1];
-	HeapScanDesc sRel;
+	HeapScanDesc scan;
 	HeapTuple	lTuple,
 				rTuple;
-	Datum		d,
-				value[Natts_pg_listener];
+	Datum		value[Natts_pg_listener];
 	char		repl[Natts_pg_listener],
 				nulls[Natts_pg_listener];
-	bool		isnull;
-	char	   *relname;
-	int32		sourcePID;

 	if (Trace_notify)
 		elog(DEBUG, "ProcessIncomingNotify");
@@ -773,7 +783,7 @@ ProcessIncomingNotify(void)
 						   Anum_pg_listener_pid,
 						   F_INT4EQ,
 						   Int32GetDatum(MyProcPid));
-	sRel = heap_beginscan(lRel, 0, SnapshotNow, 1, key);
+	scan = heap_beginscan(lRel, 0, SnapshotNow, 1, key);

 	/* Prepare data for rewriting 0 into notification field */
 	nulls[0] = nulls[1] = nulls[2] = ' ';
@@ -782,14 +792,14 @@ ProcessIncomingNotify(void)
 	value[0] = value[1] = value[2] = (Datum) 0;
 	value[Anum_pg_listener_notify - 1] = Int32GetDatum(0);

-	while (HeapTupleIsValid(lTuple = heap_getnext(sRel, 0)))
+	while (HeapTupleIsValid(lTuple = heap_getnext(scan, 0)))
 	{
-		d = heap_getattr(lTuple, Anum_pg_listener_notify, tdesc, &isnull);
-		sourcePID = DatumGetInt32(d);
+		Form_pg_listener listener = (Form_pg_listener) GETSTRUCT(lTuple);
+		char	   *relname = NameStr(listener->relname);
+		int32		sourcePID = listener->notification;
+
 		if (sourcePID != 0)
 		{
-			d = heap_getattr(lTuple, Anum_pg_listener_relname, tdesc, &isnull);
-			relname = (char *) DatumGetPointer(d);
 			/* Notify the frontend */

 			if (Trace_notify)
@@ -800,6 +810,8 @@ ProcessIncomingNotify(void)
 			/* Rewrite the tuple with 0 in notification column */
 			rTuple = heap_modifytuple(lTuple, lRel, value, nulls, repl);
 			simple_heap_update(lRel, &lTuple->t_self, rTuple);
+
+#ifdef NOT_USED					/* currently there are no indexes */
 			if (RelationGetForm(lRel)->relhasindex)
 			{
 				Relation	idescs[Num_pg_listener_indices];
@@ -808,9 +820,10 @@ ProcessIncomingNotify(void)
 				CatalogIndexInsert(idescs, Num_pg_listener_indices, lRel, rTuple);
 				CatalogCloseIndices(Num_pg_listener_indices, idescs);
 			}
+#endif
 		}
 	}
-	heap_endscan(sRel);
+	heap_endscan(scan);

 	/*
 	 * We do NOT release the lock on pg_listener here; we need to hold it
@@ -876,7 +889,7 @@ AsyncExistsPendingNotify(char *relname)
 		 p = DLGetSucc(p))
 	{
 		/* Use NAMEDATALEN for relname comparison.	  DZ - 26-08-1996 */
-		if (!strncmp((const char *) DLE_VAL(p), relname, NAMEDATALEN))
+		if (strncmp((const char *) DLE_VAL(p), relname, NAMEDATALEN) == 0)
 			return 1;
 	}

--- a/src/backend/commands/command.c
+++ b/src/backend/commands/command.c
@@ -8,7 +8,7 @@
 *
 *
 * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/commands/Attic/command.c,v 1.132 2001/06/07 00:09:28 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/commands/Attic/command.c,v 1.133 2001/06/12 05:55:49 tgl Exp $
 *
 * NOTES
 *	  The PerformAddAttribute() code, like most of the relation
@@ -411,8 +411,8 @@ AlterTableAddColumn(const char *relationName,
 	attributeD.attrelid = reltup->t_data->t_oid;

 	attributeTuple = heap_addheader(Natts_pg_attribute,
-									sizeof attributeD,
-									(char *) &attributeD);
+									ATTRIBUTE_TUPLE_SIZE,
+									(void *) &attributeD);

 	attribute = (Form_pg_attribute) GETSTRUCT(attributeTuple);

@@ -481,7 +481,7 @@ AlterTableAddColumn(const char *relationName,
 	if (hasindex)
 		CatalogCloseIndices(Num_pg_attr_indices, idescs);

-	heap_close(attrdesc, RowExclusiveLock);
+	heap_close(attrdesc, NoLock);

 	/*
 	 * Update number of attributes in pg_class tuple
@@ -580,17 +580,15 @@ AlterTableAlterColumnDefault(const char *relationName,
 						   PointerGetDatum(colName),
 						   0, 0);
 	if (!HeapTupleIsValid(tuple))
-	{
-		heap_close(rel, AccessExclusiveLock);
 		elog(ERROR, "ALTER TABLE: relation \"%s\" has no column \"%s\"",
 			 relationName, colName);
-	}

 	attnum = ((Form_pg_attribute) GETSTRUCT(tuple))->attnum;
 	ReleaseSysCache(tuple);

-	if (newDefault)				/* SET DEFAULT */
+	if (newDefault)
 	{
+		/* SET DEFAULT */
 		List	   *rawDefaults = NIL;
 		RawColumnDefault *rawEnt;

@@ -608,15 +606,14 @@ AlterTableAlterColumnDefault(const char *relationName,
 		 */
 		AddRelationRawConstraints(rel, rawDefaults, NIL);
 	}
-
 	else
-/* DROP DEFAULT */
 	{
+		/* DROP DEFAULT */
 		Relation	attr_rel;
 		ScanKeyData scankeys[3];
 		HeapScanDesc scan;

-		attr_rel = heap_openr(AttributeRelationName, AccessExclusiveLock);
+		attr_rel = heap_openr(AttributeRelationName, RowExclusiveLock);
 		ScanKeyEntryInitialize(&scankeys[0], 0x0,
 							   Anum_pg_attribute_attrelid, F_OIDEQ,
 							   ObjectIdGetDatum(myrelid));
@@ -665,7 +662,7 @@ drop_default(Oid relid, int16 attnum)
 	Relation	attrdef_rel;
 	HeapTuple	tuple;

-	attrdef_rel = heap_openr(AttrDefaultRelationName, AccessExclusiveLock);
+	attrdef_rel = heap_openr(AttrDefaultRelationName, RowExclusiveLock);
 	ScanKeyEntryInitialize(&scankeys[0], 0x0,
 						   Anum_pg_attrdef_adrelid, F_OIDEQ,
 						   ObjectIdGetDatum(relid));
@@ -778,7 +775,7 @@ AlterTableAlterColumnStatistics(const char *relationName,
 	}

 	heap_freetuple(tuple);
-	heap_close(attrelation, RowExclusiveLock);
+	heap_close(attrelation, NoLock);
 }


@@ -1010,8 +1007,7 @@ AlterTableDropColumn(const char *relationName,
 {
 #ifdef	_DROP_COLUMN_HACK__
 	Relation	rel,
-				attrdesc,
-				adrel;
+				attrdesc;
 	Oid			myrelid,
 				attoid;
 	HeapTuple	reltup;
@@ -1023,8 +1019,6 @@ AlterTableDropColumn(const char *relationName,
 	int			attnum;
 	bool		hasindex;
 	char		dropColname[32];
-	void	   *sysscan;
-	ScanKeyData scankeys[2];

 	if (inh)
 		elog(ERROR, "ALTER TABLE / DROP COLUMN with inherit option is not supported yet");
@@ -1136,30 +1130,9 @@ AlterTableDropColumn(const char *relationName,

 	/* delete comments */
 	DeleteComments(attoid);
-	/* delete attrdef */
-	adrel = heap_openr(AttrDefaultRelationName, RowExclusiveLock);
-	ScanKeyEntryInitialize(&scankeys[0], 0x0, Anum_pg_attrdef_adrelid,
-						   F_OIDEQ, ObjectIdGetDatum(myrelid));

-	/*--------
-	 * Oops pg_attrdef doesn't have (adrelid,adnum) index
-	 *
-	 *	ScanKeyEntryInitialize(&scankeys[1], 0x0, Anum_pg_attrdef_adnum,
-	 * 								F_INT2EQ, Int16GetDatum(attnum));
-	 *	sysscan = systable_beginscan(adrel, AttrDefaultIndex, 2, scankeys);
-	 *--------
-	 */
-	sysscan = systable_beginscan(adrel, AttrDefaultIndex, 1, scankeys);
-	while (HeapTupleIsValid(tup = systable_getnext(sysscan)))
-	{
-		if (((Form_pg_attrdef) GETSTRUCT(tup))->adnum == attnum)
-		{
-			simple_heap_delete(adrel, &tup->t_self);
-			break;
-		}
-	}
-	systable_endscan(sysscan);
-	heap_close(adrel, NoLock);
+	/* delete attrdef */
+	drop_default(myrelid, attnum);

 	/*
 	 * Remove objects which reference this column
@@ -1318,10 +1291,7 @@ AlterTableAddConstraint(char *relationName,
 							heap_endscan(scan);

 							if (!successful)
-							{
-								heap_close(rel, NoLock);
 								elog(ERROR, "AlterTableAddConstraint: rejected due to CHECK constraint %s", name);
-							}

 							/*
 							 * Call AddRelationRawConstraints to do the
@@ -1768,7 +1738,7 @@ AlterTableOwner(const char *relationName, const char *newOwnerName)
 	 * unlock everything and return
 	 */
 	heap_freetuple(tuple);
-	heap_close(class_rel, RowExclusiveLock);
+	heap_close(class_rel, NoLock);
 }


--- a/src/backend/commands/dbcommands.c
+++ b/src/backend/commands/dbcommands.c
@@ -1,6 +1,7 @@
 /*-------------------------------------------------------------------------
 *
 * dbcommands.c
+ *		Database management commands (create/drop database).
 *
 *
 * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
@@ -8,7 +9,7 @@
 *
 *
 * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/commands/dbcommands.c,v 1.74 2001/03/22 03:59:22 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/commands/dbcommands.c,v 1.75 2001/06/12 05:55:49 tgl Exp $
 *
 *-------------------------------------------------------------------------
 */
@@ -25,6 +26,7 @@
 #include "catalog/catalog.h"
 #include "catalog/pg_database.h"
 #include "catalog/pg_shadow.h"
+#include "catalog/indexing.h"
 #include "commands/comment.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
@@ -241,9 +243,8 @@ createdb(const char *dbname, const char *dbpath,
 	heap_insert(pg_database_rel, tuple);

 	/*
-	 * Update indexes (there aren't any currently)
+	 * Update indexes
 	 */
-#ifdef Num_pg_database_indices
 	if (RelationGetForm(pg_database_rel)->relhasindex)
 	{
 		Relation	idescs[Num_pg_database_indices];
@@ -254,7 +255,6 @@ createdb(const char *dbname, const char *dbpath,
 						   tuple);
 		CatalogCloseIndices(Num_pg_database_indices, idescs);
 	}
-#endif

 	/* Close pg_database, but keep lock till commit */
 	heap_close(pg_database_rel, NoLock);
@@ -333,7 +333,7 @@ dropdb(const char *dbname)
 		elog(ERROR, "DROP DATABASE: database \"%s\" is being accessed by other users", dbname);

 	/*
-	 * Find the database's tuple by OID (should be unique, we trust).
+	 * Find the database's tuple by OID (should be unique).
 	 */
 	ScanKeyEntryInitialize(&key, 0, ObjectIdAttributeNumber,
 						   F_OIDEQ, ObjectIdGetDatum(db_id));
@@ -343,7 +343,6 @@ dropdb(const char *dbname)
 	tup = heap_getnext(pgdbscan, 0);
 	if (!HeapTupleIsValid(tup))
 	{
-
 		/*
 		 * This error should never come up since the existence of the
 		 * database is checked earlier
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -6,17 +6,17 @@
 * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
- * $Header: /cvsroot/pgsql/src/backend/commands/user.c,v 1.75 2001/03/22 06:16:12 momjian Exp $
+ * $Header: /cvsroot/pgsql/src/backend/commands/user.c,v 1.76 2001/06/12 05:55:49 tgl Exp $
 *
 *-------------------------------------------------------------------------
 */
+#include "postgres.h"
+
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>
 #include <unistd.h>

-#include "postgres.h"
-
 #include "access/heapam.h"
 #include "catalog/catname.h"
 #include "catalog/pg_database.h"
@@ -31,9 +31,9 @@
 #include "utils/fmgroids.h"
 #include "utils/syscache.h"

+
 static void CheckPgUserAclNotNull(void);

-#define SQL_LENGTH	512

 /*---------------------------------------------------------------------
 * write_password_file / update_pg_pwd
@@ -121,8 +121,7 @@ write_password_file(Relation rel)
 				"%s"
 				CRYPT_PWD_FILE_SEPSTR
 				"%s\n",
-				DatumGetCString(DirectFunctionCall1(nameout,
-								   NameGetDatum(DatumGetName(datum_n)))),
+				DatumGetCString(DirectFunctionCall1(nameout, datum_n)),
 				null_p ? "" :
 				DatumGetCString(DirectFunctionCall1(textout, datum_p)),
 				null_v ? "\\N" :
@@ -168,10 +167,16 @@ write_password_file(Relation rel)
 Datum
 update_pg_pwd(PG_FUNCTION_ARGS)
 {
-	Relation	rel = heap_openr(ShadowRelationName, AccessExclusiveLock);
+	/*
+	 * ExclusiveLock ensures no one modifies pg_shadow while we read it,
+	 * and that only one backend rewrites the flat file at a time.  It's
+	 * OK to allow normal reads of pg_shadow in parallel, however.
+	 */
+	Relation	rel = heap_openr(ShadowRelationName, ExclusiveLock);

 	write_password_file(rel);
-	heap_close(rel, AccessExclusiveLock);
+	/* OK to release lock, since we did not modify the relation */
+	heap_close(rel, ExclusiveLock);
 	return PointerGetDatum(NULL);
 }

@@ -210,39 +215,41 @@ CreateUser(CreateUserStmt *stmt)
 	 * to be sure of what the next usesysid should be, and we need to
 	 * protect our update of the flat password file.
 	 */
-	pg_shadow_rel = heap_openr(ShadowRelationName, AccessExclusiveLock);
+	pg_shadow_rel = heap_openr(ShadowRelationName, ExclusiveLock);
 	pg_shadow_dsc = RelationGetDescr(pg_shadow_rel);

 	scan = heap_beginscan(pg_shadow_rel, false, SnapshotNow, 0, NULL);
-	while (!user_exists && !sysid_exists && HeapTupleIsValid(tuple = heap_getnext(scan, 0)))
+	while (!user_exists && !sysid_exists &&
+		   HeapTupleIsValid(tuple = heap_getnext(scan, 0)))
 	{
 		Datum		datum;
 		bool		null;

-		datum = heap_getattr(tuple, Anum_pg_shadow_usename, pg_shadow_dsc, &null);
-		user_exists = datum && !null && (strcmp((char *) datum, stmt->user) == 0);
+		datum = heap_getattr(tuple, Anum_pg_shadow_usename,
+							 pg_shadow_dsc, &null);
+		Assert(!null);
+		user_exists = (strcmp((char *) DatumGetName(datum), stmt->user) == 0);

-		datum = heap_getattr(tuple, Anum_pg_shadow_usesysid, pg_shadow_dsc, &null);
+		datum = heap_getattr(tuple, Anum_pg_shadow_usesysid,
+							 pg_shadow_dsc, &null);
+		Assert(!null);
 		if (havesysid)			/* customized id wanted */
-			sysid_exists = datum && !null && ((int) datum == stmt->sysid);
+			sysid_exists = (DatumGetInt32(datum) == stmt->sysid);
 		else
-/* pick 1 + max */
 		{
-			if ((int) datum > max_id)
-				max_id = (int) datum;
+			/* pick 1 + max */
+			if (DatumGetInt32(datum) > max_id)
+				max_id = DatumGetInt32(datum);
 		}
 	}
 	heap_endscan(scan);

-	if (user_exists || sysid_exists)
-	{
-		heap_close(pg_shadow_rel, AccessExclusiveLock);
-		if (user_exists)
-			elog(ERROR, "CREATE USER: user name \"%s\" already exists", stmt->user);
-		else
-			elog(ERROR, "CREATE USER: sysid %d is already assigned", stmt->sysid);
-		return;
-	}
+	if (user_exists)
+		elog(ERROR, "CREATE USER: user name \"%s\" already exists",
+			 stmt->user);
+	if (sysid_exists)
+		elog(ERROR, "CREATE USER: sysid %d is already assigned",
+			 stmt->sysid);

 	/*
 	 * Build a tuple to insert
@@ -252,12 +259,12 @@ CreateUser(CreateUserStmt *stmt)
 	new_record[Anum_pg_shadow_usesysid - 1] = Int32GetDatum(havesysid ? stmt->sysid : max_id + 1);

 	AssertState(BoolIsValid(stmt->createdb));
-	new_record[Anum_pg_shadow_usecreatedb - 1] = (Datum) (stmt->createdb);
-	new_record[Anum_pg_shadow_usetrace - 1] = (Datum) (false);
+	new_record[Anum_pg_shadow_usecreatedb - 1] = BoolGetDatum(stmt->createdb);
+	new_record[Anum_pg_shadow_usetrace - 1] = BoolGetDatum(false);
 	AssertState(BoolIsValid(stmt->createuser));
-	new_record[Anum_pg_shadow_usesuper - 1] = (Datum) (stmt->createuser);
+	new_record[Anum_pg_shadow_usesuper - 1] = BoolGetDatum(stmt->createuser);
 	/* superuser gets catupd right by default */
-	new_record[Anum_pg_shadow_usecatupd - 1] = (Datum) (stmt->createuser);
+	new_record[Anum_pg_shadow_usecatupd - 1] = BoolGetDatum(stmt->createuser);

 	if (stmt->password)
 		new_record[Anum_pg_shadow_passwd - 1] =
@@ -278,13 +285,11 @@ CreateUser(CreateUserStmt *stmt)
 	new_record_nulls[Anum_pg_shadow_valuntil - 1] = stmt->validUntil ? ' ' : 'n';

 	tuple = heap_formtuple(pg_shadow_dsc, new_record, new_record_nulls);
-	Assert(tuple);

 	/*
-	 * Insert a new record in the pg_shadow table
+	 * Insert new record in the pg_shadow table
 	 */
-	if (heap_insert(pg_shadow_rel, tuple) == InvalidOid)
-		elog(ERROR, "CREATE USER: heap_insert failed");
+	heap_insert(pg_shadow_rel, tuple);

 	/*
 	 * Update indexes
@@ -322,9 +327,9 @@ CreateUser(CreateUserStmt *stmt)
 	write_password_file(pg_shadow_rel);

 	/*
-	 * Now we can clean up.
+	 * Now we can clean up; but keep lock until commit.
 	 */
-	heap_close(pg_shadow_rel, AccessExclusiveLock);
+	heap_close(pg_shadow_rel, NoLock);
 }


@@ -348,8 +353,11 @@ AlterUser(AlterUserStmt *stmt)

 	/* must be superuser or just want to change your own password */
 	if (!superuser() &&
-	  !(stmt->createdb == 0 && stmt->createuser == 0 && !stmt->validUntil
-		&& stmt->password && strcmp(GetUserName(GetUserId()), stmt->user) == 0))
+		!(stmt->createdb == 0 &&
+		  stmt->createuser == 0 &&
+		  !stmt->validUntil &&
+		  stmt->password &&
+		  strcmp(GetUserName(GetUserId()), stmt->user) == 0))
 		elog(ERROR, "ALTER USER: permission denied");

 	/* changes to the flat password file cannot be rolled back */
@@ -361,17 +369,14 @@ AlterUser(AlterUserStmt *stmt)
 	 * secure exclusive lock to protect our update of the flat password
 	 * file.
 	 */
-	pg_shadow_rel = heap_openr(ShadowRelationName, AccessExclusiveLock);
+	pg_shadow_rel = heap_openr(ShadowRelationName, ExclusiveLock);
 	pg_shadow_dsc = RelationGetDescr(pg_shadow_rel);

 	tuple = SearchSysCache(SHADOWNAME,
 						   PointerGetDatum(stmt->user),
 						   0, 0, 0);
 	if (!HeapTupleIsValid(tuple))
-	{
-		heap_close(pg_shadow_rel, AccessExclusiveLock);
 		elog(ERROR, "ALTER USER: user \"%s\" does not exist", stmt->user);
-	}

 	/*
 	 * Build a tuple to update, perusing the information just obtained
@@ -483,8 +488,7 @@ AlterUser(AlterUserStmt *stmt)
 	/*
 	 * Now we can clean up.
 	 */
-	heap_close(pg_shadow_rel, AccessExclusiveLock);
-
+	heap_close(pg_shadow_rel, NoLock);
 }


@@ -510,7 +514,7 @@ DropUser(DropUserStmt *stmt)
 	 * deleted.  Note we secure exclusive lock, because we need to protect
 	 * our update of the flat password file.
 	 */
-	pg_shadow_rel = heap_openr(ShadowRelationName, AccessExclusiveLock);
+	pg_shadow_rel = heap_openr(ShadowRelationName, ExclusiveLock);
 	pg_shadow_dsc = RelationGetDescr(pg_shadow_rel);

 	foreach(item, stmt->users)
@@ -530,11 +534,8 @@ DropUser(DropUserStmt *stmt)
 							   PointerGetDatum(user),
 							   0, 0, 0);
 		if (!HeapTupleIsValid(tuple))
-		{
-			heap_close(pg_shadow_rel, AccessExclusiveLock);
 			elog(ERROR, "DROP USER: user \"%s\" does not exist%s", user,
 				 (length(stmt->users) > 1) ? " (no users removed)" : "");
-		}

 		usesysid = DatumGetInt32(heap_getattr(tuple, Anum_pg_shadow_usesysid, pg_shadow_dsc, &null));

@@ -546,28 +547,30 @@ DropUser(DropUserStmt *stmt)
 		 * don't read the manual, it doesn't seem to be the behaviour one
 		 * would expect either.) -- petere 2000/01/14)
 		 */
-		pg_rel = heap_openr(DatabaseRelationName, AccessExclusiveLock);
+		pg_rel = heap_openr(DatabaseRelationName, AccessShareLock);
 		pg_dsc = RelationGetDescr(pg_rel);

-		ScanKeyEntryInitialize(&scankey, 0x0, Anum_pg_database_datdba, F_INT4EQ,
+		ScanKeyEntryInitialize(&scankey, 0x0,
+							   Anum_pg_database_datdba, F_INT4EQ,
 							   Int32GetDatum(usesysid));

 		scan = heap_beginscan(pg_rel, false, SnapshotNow, 1, &scankey);

 		if (HeapTupleIsValid(tmp_tuple = heap_getnext(scan, 0)))
 		{
-			datum = heap_getattr(tmp_tuple, Anum_pg_database_datname, pg_dsc, &null);
-			heap_close(pg_shadow_rel, AccessExclusiveLock);
+			char   *dbname;
+
+			datum = heap_getattr(tmp_tuple, Anum_pg_database_datname,
+								 pg_dsc, &null);
+			Assert(!null);
+			dbname = DatumGetCString(DirectFunctionCall1(nameout, datum));
 			elog(ERROR, "DROP USER: user \"%s\" owns database \"%s\", cannot be removed%s",
-				 user,
-				 DatumGetCString(DirectFunctionCall1(nameout,
-									 NameGetDatum(DatumGetName(datum)))),
-				 (length(stmt->users) > 1) ? " (no users removed)" : ""
-				);
+				 user, dbname,
+				 (length(stmt->users) > 1) ? " (no users removed)" : "");
 		}

 		heap_endscan(scan);
-		heap_close(pg_rel, AccessExclusiveLock);
+		heap_close(pg_rel, AccessShareLock);

 		/*
 		 * Somehow we'd have to check for tables, views, etc. owned by the
@@ -587,7 +590,7 @@ DropUser(DropUserStmt *stmt)
 		 *
 		 * try calling alter group drop user for every group
 		 */
-		pg_rel = heap_openr(GroupRelationName, AccessExclusiveLock);
+		pg_rel = heap_openr(GroupRelationName, ExclusiveLock);
 		pg_dsc = RelationGetDescr(pg_rel);
 		scan = heap_beginscan(pg_rel, false, SnapshotNow, 0, NULL);
 		while (HeapTupleIsValid(tmp_tuple = heap_getnext(scan, 0)))
@@ -602,7 +605,7 @@ DropUser(DropUserStmt *stmt)
 			AlterGroup(&ags, "DROP USER");
 		}
 		heap_endscan(scan);
-		heap_close(pg_rel, AccessExclusiveLock);
+		heap_close(pg_rel, ExclusiveLock);

 		/*
 		 * Advance command counter so that later iterations of this loop
@@ -622,7 +625,7 @@ DropUser(DropUserStmt *stmt)
 	/*
 	 * Now we can clean up.
 	 */
-	heap_close(pg_shadow_rel, AccessExclusiveLock);
+	heap_close(pg_shadow_rel, NoLock);
 }


@@ -681,38 +684,41 @@ CreateGroup(CreateGroupStmt *stmt)
 	if (!superuser())
 		elog(ERROR, "CREATE GROUP: permission denied");

-	pg_group_rel = heap_openr(GroupRelationName, AccessExclusiveLock);
+	pg_group_rel = heap_openr(GroupRelationName, ExclusiveLock);
 	pg_group_dsc = RelationGetDescr(pg_group_rel);

 	scan = heap_beginscan(pg_group_rel, false, SnapshotNow, 0, NULL);
-	while (!group_exists && !sysid_exists && HeapTupleIsValid(tuple = heap_getnext(scan, false)))
+	while (!group_exists && !sysid_exists &&
+		   HeapTupleIsValid(tuple = heap_getnext(scan, false)))
 	{
 		Datum		datum;
 		bool		null;

-		datum = heap_getattr(tuple, Anum_pg_group_groname, pg_group_dsc, &null);
-		group_exists = datum && !null && (strcmp((char *) datum, stmt->name) == 0);
+		datum = heap_getattr(tuple, Anum_pg_group_groname,
+							 pg_group_dsc, &null);
+		Assert(!null);
+		group_exists = (strcmp((char *) DatumGetName(datum), stmt->name) == 0);

-		datum = heap_getattr(tuple, Anum_pg_group_grosysid, pg_group_dsc, &null);
+		datum = heap_getattr(tuple, Anum_pg_group_grosysid,
+							 pg_group_dsc, &null);
+		Assert(!null);
 		if (stmt->sysid >= 0)	/* customized id wanted */
-			sysid_exists = datum && !null && ((int) datum == stmt->sysid);
+			sysid_exists = (DatumGetInt32(datum) == stmt->sysid);
 		else
-/* pick 1 + max */
 		{
-			if ((int) datum > max_id)
-				max_id = (int) datum;
+			/* pick 1 + max */
+			if (DatumGetInt32(datum) > max_id)
+				max_id = DatumGetInt32(datum);
 		}
 	}
 	heap_endscan(scan);

-	if (group_exists || sysid_exists)
-	{
-		heap_close(pg_group_rel, AccessExclusiveLock);
-		if (group_exists)
-			elog(ERROR, "CREATE GROUP: group name \"%s\" already exists", stmt->name);
-		else
-			elog(ERROR, "CREATE GROUP: group sysid %d is already assigned", stmt->sysid);
-	}
+	if (group_exists)
+		elog(ERROR, "CREATE GROUP: group name \"%s\" already exists",
+			 stmt->name);
+	if (sysid_exists)
+		elog(ERROR, "CREATE GROUP: group sysid %d is already assigned",
+			 stmt->sysid);

 	/*
 	 * Translate the given user names to ids
@@ -790,7 +796,7 @@ CreateGroup(CreateGroupStmt *stmt)
 		CatalogCloseIndices(Num_pg_group_indices, idescs);
 	}

-	heap_close(pg_group_rel, AccessExclusiveLock);
+	heap_close(pg_group_rel, NoLock);
 }


@@ -811,7 +817,7 @@ AlterGroup(AlterGroupStmt *stmt, const char *tag)
 	if (!superuser())
 		elog(ERROR, "%s: permission denied", tag);

-	pg_group_rel = heap_openr(GroupRelationName, AccessExclusiveLock);
+	pg_group_rel = heap_openr(GroupRelationName, ExclusiveLock);
 	pg_group_dsc = RelationGetDescr(pg_group_rel);

 	/*
@@ -1052,7 +1058,7 @@ AlterGroup(AlterGroupStmt *stmt, const char *tag)

 	ReleaseSysCache(group_tuple);

-	heap_close(pg_group_rel, AccessExclusiveLock);
+	heap_close(pg_group_rel, NoLock);
 }


@@ -1078,7 +1084,7 @@ DropGroup(DropGroupStmt *stmt)
 	/*
 	 * Scan the pg_group table and delete all matching groups.
 	 */
-	pg_group_rel = heap_openr(GroupRelationName, AccessExclusiveLock);
+	pg_group_rel = heap_openr(GroupRelationName, ExclusiveLock);
 	pg_group_dsc = RelationGetDescr(pg_group_rel);
 	scan = heap_beginscan(pg_group_rel, false, SnapshotNow, 0, NULL);

@@ -1087,8 +1093,9 @@ DropGroup(DropGroupStmt *stmt)
 		Datum		datum;
 		bool		null;

-		datum = heap_getattr(tuple, Anum_pg_group_groname, pg_group_dsc, &null);
-		if (datum && !null && strcmp((char *) datum, stmt->name) == 0)
+		datum = heap_getattr(tuple, Anum_pg_group_groname,
+							 pg_group_dsc, &null);
+		if (!null && strcmp((char *) DatumGetName(datum), stmt->name) == 0)
 		{
 			gro_exists = true;
 			simple_heap_delete(pg_group_rel, &tuple->t_self);
@@ -1101,10 +1108,7 @@ DropGroup(DropGroupStmt *stmt)
 	 * Did we find any?
 	 */
 	if (!gro_exists)
-	{
-		heap_close(pg_group_rel, AccessExclusiveLock);
 		elog(ERROR, "DROP GROUP: group \"%s\" does not exist", stmt->name);
-	}

-	heap_close(pg_group_rel, AccessExclusiveLock);
+	heap_close(pg_group_rel, NoLock);
 }