Modify the relcache to record the temp status of both local and nonlocal

temp relations; this is no more expensive than before, now that we have
pg_class.relistemp.  Insert tests into bufmgr.c to prevent attempting
to fetch pages from nonlocal temp relations.  This provides a low-level
defense against bugs-of-omission allowing temp pages to be loaded into shared
buffers, as in the contrib/pgstattuple problem reported by Stuart Bishop.
While at it, tweak a bunch of places to use new relcache tests (instead of
expensive probes into pg_namespace) to detect local or nonlocal temp tables.

src/backend/catalog/index.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/catalog/index.c,v 1.314 2009/03/27 15:57:11 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/catalog/index.c,v 1.315 2009/03/31 22:12:46 tgl Exp $
  *
  *
  * INTERFACE ROUTINES
@@ -2264,7 +2264,7 @@ reindex_index(Oid indexId)
 	 * Don't allow reindex on temp tables of other backends ... their local
 	 * buffer manager is not going to cope.
 	 */
-	if (isOtherTempNamespace(RelationGetNamespace(iRel)))
+	if (RELATION_IS_OTHER_TEMP(iRel))
 		ereport(ERROR,
 				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 				 errmsg("cannot reindex temporary tables of other sessions")));

src/backend/catalog/namespace.c

@@ -13,7 +13,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/catalog/namespace.c,v 1.116 2009/01/01 17:23:37 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/catalog/namespace.c,v 1.117 2009/03/31 22:12:46 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -2389,6 +2389,9 @@ isAnyTempNamespace(Oid namespaceId)
 /*
  * isOtherTempNamespace - is the given namespace some other backend's
  * temporary-table namespace (including temporary-toast-table namespaces)?
+ *
+ * Note: for most purposes in the C code, this function is obsolete.  Use
+ * RELATION_IS_OTHER_TEMP() instead to detect non-local temp relations.
  */
 bool
 isOtherTempNamespace(Oid namespaceId)

src/backend/catalog/toasting.c

@@ -8,7 +8,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/catalog/toasting.c,v 1.13 2009/02/02 19:31:38 alvherre Exp $
+ *	  $PostgreSQL: pgsql/src/backend/catalog/toasting.c,v 1.14 2009/03/31 22:12:46 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -179,7 +179,7 @@ create_toast_table(Relation rel, Oid toastOid, Oid toastIndexOid, Datum reloptio
 	 * Toast tables for regular relations go in pg_toast; those for temp
 	 * relations go into the per-backend temp-toast-table namespace.
 	 */
-	if (rel->rd_istemp)
+	if (rel->rd_islocaltemp)
 		namespaceid = GetTempToastNamespace();
 	else
 		namespaceid = PG_TOAST_NAMESPACE;

src/backend/commands/analyze.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/analyze.c,v 1.134 2009/03/24 20:17:13 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/analyze.c,v 1.135 2009/03/31 22:12:46 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -213,7 +213,7 @@ analyze_rel(Oid relid, VacuumStmt *vacstmt,
 	 * probably not up-to-date on disk.  (We don't throw a warning here; it
 	 * would just lead to chatter during a database-wide ANALYZE.)
 	 */
-	if (isOtherTempNamespace(RelationGetNamespace(onerel)))
+	if (RELATION_IS_OTHER_TEMP(onerel))
 	{
 		relation_close(onerel, ShareUpdateExclusiveLock);
 		return;

src/backend/commands/cluster.c

@@ -11,7 +11,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/cluster.c,v 1.182 2009/02/02 19:31:38 alvherre Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/cluster.c,v 1.183 2009/03/31 22:12:46 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -117,7 +117,7 @@ cluster(ClusterStmt *stmt, bool isTopLevel)
 		 * Reject clustering a remote temp table ... their local buffer
 		 * manager is not going to cope.
 		 */
-		if (isOtherTempNamespace(RelationGetNamespace(rel)))
+		if (RELATION_IS_OTHER_TEMP(rel))
 			ereport(ERROR,
 					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 			   errmsg("cannot cluster temporary tables of other sessions")));
@@ -302,7 +302,7 @@ cluster_rel(RelToCluster *rvtc, bool recheck, bool verbose)
 		 * check_index_is_clusterable which is redundant, but we leave it for
 		 * extra safety.
 		 */
-		if (isOtherTempNamespace(RelationGetNamespace(OldHeap)))
+		if (RELATION_IS_OTHER_TEMP(OldHeap))
 		{
 			relation_close(OldHeap, AccessExclusiveLock);
 			return;
@@ -465,7 +465,7 @@ check_index_is_clusterable(Relation OldHeap, Oid indexOid, bool recheck)
 	 * Don't allow cluster on temp tables of other backends ... their local
 	 * buffer manager is not going to cope.
 	 */
-	if (isOtherTempNamespace(RelationGetNamespace(OldHeap)))
+	if (RELATION_IS_OTHER_TEMP(OldHeap))
 		ereport(ERROR,
 				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 			   errmsg("cannot cluster temporary tables of other sessions")));

src/backend/commands/copy.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/copy.c,v 1.306 2009/03/26 19:24:54 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/copy.c,v 1.307 2009/03/31 22:12:46 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1001,8 +1001,7 @@ DoCopy(const CopyStmt *stmt, const char *queryString)
 		}
 
 		/* check read-only transaction */
-		if (XactReadOnly && is_from &&
-			!isTempNamespace(RelationGetNamespace(cstate->rel)))
+		if (XactReadOnly && is_from && !cstate->rel->rd_islocaltemp)
 			ereport(ERROR,
 					(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
 					 errmsg("transaction is read-only")));

src/backend/commands/indexcmds.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/indexcmds.c,v 1.182 2009/02/02 19:31:38 alvherre Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/indexcmds.c,v 1.183 2009/03/31 22:12:47 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -175,7 +175,7 @@ DefineIndex(RangeVar *heapRelation,
 	/*
 	 * Don't try to CREATE INDEX on temp tables of other backends.
 	 */
-	if (isOtherTempNamespace(namespaceId))
+	if (RELATION_IS_OTHER_TEMP(rel))
 		ereport(ERROR,
 				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 				 errmsg("cannot create indexes on temporary tables of other sessions")));
@@ -1404,7 +1404,8 @@ ReindexDatabase(const char *databaseName, bool do_system, bool do_user)
 			continue;
 
 		/* Skip temp tables of other backends; we can't reindex them at all */
-		if (isOtherTempNamespace(classtuple->relnamespace))
+		if (classtuple->relistemp &&
+			!isTempNamespace(classtuple->relnamespace))
 			continue;
 
 		/* Check user/system classification, and optionally skip */

src/backend/commands/tablecmds.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.280 2009/02/11 21:11:16 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.281 2009/03/31 22:12:47 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1056,7 +1056,7 @@ truncate_check_rel(Relation rel)
 	 * Don't allow truncate on temp tables of other backends ... their local
 	 * buffer manager is not going to cope.
 	 */
-	if (isOtherTempNamespace(RelationGetNamespace(rel)))
+	if (RELATION_IS_OTHER_TEMP(rel))
 		ereport(ERROR,
 				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 			  errmsg("cannot truncate temporary tables of other sessions")));
@@ -1203,7 +1203,7 @@ MergeAttributes(List *schema, List *supers, bool istemp,
 					 errmsg("inherited relation \"%s\" is not a table",
 							parent->relname)));
 		/* Permanent rels cannot inherit from temporary ones */
-		if (!istemp && isTempNamespace(RelationGetNamespace(relation)))
+		if (!istemp && relation->rd_istemp)
 			ereport(ERROR,
 					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
 					 errmsg("cannot inherit from temporary relation \"%s\"",
@@ -2793,7 +2793,7 @@ ATRewriteTables(List **wqueue)
 			 * Don't allow rewrite on temp tables of other backends ... their
 			 * local buffer manager is not going to cope.
 			 */
-			if (isOtherTempNamespace(RelationGetNamespace(OldHeap)))
+			if (RELATION_IS_OTHER_TEMP(OldHeap))
 				ereport(ERROR,
 						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 				errmsg("cannot rewrite temporary tables of other sessions")));
@@ -4603,16 +4603,16 @@ ATAddForeignKeyConstraint(AlteredTableInfo *tab, Relation rel,
 	 * backend has created in the temp table, because non-shared buffers are
 	 * used for temp tables.)
 	 */
-	if (isTempNamespace(RelationGetNamespace(pkrel)))
+	if (pkrel->rd_istemp)
 	{
-		if (!isTempNamespace(RelationGetNamespace(rel)))
+		if (!rel->rd_istemp)
 			ereport(ERROR,
 					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
 					 errmsg("cannot reference temporary table from permanent table constraint")));
 	}
 	else
 	{
-		if (isTempNamespace(RelationGetNamespace(rel)))
+		if (rel->rd_istemp)
 			ereport(ERROR,
 					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
 					 errmsg("cannot reference permanent table from temporary table constraint")));
@@ -6690,7 +6690,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace)
 	 * Don't allow moving temp tables of other backends ... their local buffer
 	 * manager is not going to cope.
 	 */
-	if (isOtherTempNamespace(RelationGetNamespace(rel)))
+	if (RELATION_IS_OTHER_TEMP(rel))
 		ereport(ERROR,
 				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 				 errmsg("cannot move temporary tables of other sessions")));
@@ -6901,8 +6901,7 @@ ATExecAddInherit(Relation child_rel, RangeVar *parent)
 	ATSimplePermissions(parent_rel, false);
 
 	/* Permanent rels cannot inherit from temporary ones */
-	if (!isTempNamespace(RelationGetNamespace(child_rel)) &&
-		isTempNamespace(RelationGetNamespace(parent_rel)))
+	if (parent_rel->rd_istemp && !child_rel->rd_istemp)
 		ereport(ERROR,
 				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
 				 errmsg("cannot inherit from temporary relation \"%s\"",

src/backend/commands/vacuum.c

@@ -13,7 +13,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/vacuum.c,v 1.386 2009/03/24 20:17:13 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/vacuum.c,v 1.387 2009/03/31 22:12:48 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1147,7 +1147,7 @@ vacuum_rel(Oid relid, VacuumStmt *vacstmt, bool do_toast, bool for_wraparound,
 	 * warning here; it would just lead to chatter during a database-wide
 	 * VACUUM.)
 	 */
-	if (isOtherTempNamespace(RelationGetNamespace(onerel)))
+	if (RELATION_IS_OTHER_TEMP(onerel))
 	{
 		relation_close(onerel, lmode);
 		PopActiveSnapshot();

src/backend/optimizer/prep/prepunion.c

@@ -22,7 +22,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/prep/prepunion.c,v 1.167 2009/03/05 17:30:29 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/prep/prepunion.c,v 1.168 2009/03/31 22:12:48 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1258,21 +1258,23 @@ expand_inherited_rtentry(PlannerInfo *root, RangeTblEntry *rte, Index rti)
 		Index		childRTindex;
 		AppendRelInfo *appinfo;
 
+		/* Open rel, acquire the appropriate lock type */
+		if (childOID != parentOID)
+			newrelation = heap_open(childOID, lockmode);
+		else
+			newrelation = oldrelation;
+
 		/*
 		 * It is possible that the parent table has children that are temp
 		 * tables of other backends.  We cannot safely access such tables
 		 * (because of buffering issues), and the best thing to do seems to be
 		 * to silently ignore them.
 		 */
-		if (childOID != parentOID &&
-			isOtherTempNamespace(get_rel_namespace(childOID)))
+		if (childOID != parentOID && RELATION_IS_OTHER_TEMP(newrelation))
+		{
+			heap_close(newrelation, lockmode);
 			continue;
-
-		/* Open rel, acquire the appropriate lock type */
-		if (childOID != parentOID)
-			newrelation = heap_open(childOID, lockmode);
-		else
-			newrelation = oldrelation;
+		}
 
 		/*
 		 * Build an RTE for the child, and attach to query's rangetable list.

src/backend/postmaster/autovacuum.c

@@ -55,7 +55,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/postmaster/autovacuum.c,v 1.93 2009/02/09 20:57:59 alvherre Exp $
+ *	  $PostgreSQL: pgsql/src/backend/postmaster/autovacuum.c,v 1.94 2009/03/31 22:12:48 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1942,7 +1942,6 @@ do_autovacuum(void)
 		bool		dovacuum;
 		bool		doanalyze;
 		bool		wraparound;
-		int			backendID;
 
 		relid = HeapTupleGetOid(tuple);
 
@@ -1959,10 +1958,12 @@ do_autovacuum(void)
 		 * Check if it is a temp table (presumably, of some other backend's).
 		 * We cannot safely process other backends' temp tables.
 		 */
-		backendID = GetTempNamespaceBackendId(classForm->relnamespace);
-
-		if (backendID > 0)
+		if (classForm->relistemp)
 		{
+			int			backendID;
+
+			backendID = GetTempNamespaceBackendId(classForm->relnamespace);
+
 			/* We just ignore it if the owning backend is still active */
 			if (backendID == MyBackendId || !BackendIdIsActive(backendID))
 			{
@@ -2052,10 +2053,9 @@ do_autovacuum(void)
 		bool		wraparound;
 
 		/*
-		 * Skip temp tables (i.e. those in temp namespaces).  We cannot safely
-		 * process other backends' temp tables.
+		 * We cannot safely process other backends' temp tables, so skip 'em.
 		 */
-		if (isAnyTempNamespace(classForm->relnamespace))
+		if (classForm->relistemp)
 			continue;
 
 		relid = HeapTupleGetOid(tuple);

src/backend/storage/buffer/bufmgr.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/storage/buffer/bufmgr.c,v 1.249 2009/03/23 01:52:38 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/storage/buffer/bufmgr.c,v 1.250 2009/03/31 22:12:48 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -122,6 +122,12 @@ PrefetchBuffer(Relation reln, ForkNumber forkNum, BlockNumber blockNum)
 
 	if (reln->rd_istemp)
 	{
+		/* see comments in ReadBufferExtended */
+		if (RELATION_IS_OTHER_TEMP(reln))
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("cannot access temporary tables of other sessions")));
+
 		/* pass it off to localbuf.c */
 		LocalPrefetchBuffer(reln->rd_smgr, forkNum, blockNum);
 	}
@@ -204,6 +210,16 @@ ReadBufferExtended(Relation reln, ForkNumber forkNum, BlockNumber blockNum,
 	/* Open it at the smgr level if not already done */
 	RelationOpenSmgr(reln);
 
+	/*
+	 * Reject attempts to read non-local temporary relations; we would
+	 * be likely to get wrong data since we have no visibility into the
+	 * owning session's local buffers.
+	 */
+	if (RELATION_IS_OTHER_TEMP(reln))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot access temporary tables of other sessions")));
+
 	/*
 	 * Read the buffer, and update pgstat counters to reflect a cache
 	 * hit or miss.
@@ -220,6 +236,8 @@ ReadBufferExtended(Relation reln, ForkNumber forkNum, BlockNumber blockNum,
 /*
  * ReadBufferWithoutRelcache -- like ReadBufferExtended, but doesn't require
  *		a relcache entry for the relation.
+ *
+ * NB: caller is assumed to know what it's doing if isTemp is true.
  */
 Buffer
 ReadBufferWithoutRelcache(RelFileNode rnode, bool isTemp,

src/backend/utils/cache/relcache.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/cache/relcache.c,v 1.285 2009/03/31 17:59:56 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/cache/relcache.c,v 1.286 2009/03/31 22:12:48 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -829,7 +829,11 @@ RelationBuildDesc(Oid targetRelId, Relation oldrelation)
 	relation->rd_isnailed = false;
 	relation->rd_createSubid = InvalidSubTransactionId;
 	relation->rd_newRelfilenodeSubid = InvalidSubTransactionId;
-	relation->rd_istemp = isTempOrToastNamespace(relation->rd_rel->relnamespace);
+	relation->rd_istemp = relation->rd_rel->relistemp;
+	if (relation->rd_istemp)
+		relation->rd_islocaltemp = isTempOrToastNamespace(relation->rd_rel->relnamespace);
+	else
+		relation->rd_islocaltemp = false;
 
 	/*
 	 * initialize the tuple descriptor (relation->rd_att).
@@ -1375,6 +1379,7 @@ formrdesc(const char *relationName, Oid relationReltype,
 	relation->rd_createSubid = InvalidSubTransactionId;
 	relation->rd_newRelfilenodeSubid = InvalidSubTransactionId;
 	relation->rd_istemp = false;
+	relation->rd_islocaltemp = false;
 
 	/*
 	 * initialize relation tuple form
@@ -2355,8 +2360,9 @@ RelationBuildLocalRelation(const char *relname,
 	/* must flag that we have rels created in this transaction */
 	need_eoxact_work = true;
 
-	/* is it a temporary relation? */
+	/* it is temporary if and only if it is in my temp-table namespace */
 	rel->rd_istemp = isTempOrToastNamespace(relnamespace);
+	rel->rd_islocaltemp = rel->rd_istemp;
 
 	/*
 	 * create a new tuple descriptor from the one passed in.  We do this
@@ -2403,9 +2409,7 @@ RelationBuildLocalRelation(const char *relname,
 	 * as the logical ID (OID).
 	 */
 	rel->rd_rel->relisshared = shared_relation;
-
-	/* it is temporary if and only if it is in my temp-table namespace */
-	rel->rd_rel->relistemp = isTempOrToastNamespace(relnamespace);
+	rel->rd_rel->relistemp = rel->rd_istemp;
 
 	RelationGetRelid(rel) = relid;
 

src/include/utils/rel.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/utils/rel.h,v 1.112 2009/02/09 20:57:59 alvherre Exp $
+ * $PostgreSQL: pgsql/src/include/utils/rel.h,v 1.113 2009/03/31 22:12:48 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -126,7 +126,8 @@ typedef struct RelationData
 	BlockNumber rd_targblock;	/* current insertion target block, or
 								 * InvalidBlockNumber */
 	int			rd_refcnt;		/* reference count */
-	bool		rd_istemp;		/* rel uses the local buffer mgr */
+	bool		rd_istemp;		/* rel is a temporary relation */
+	bool		rd_islocaltemp;	/* rel is a temp rel of this session */
 	bool		rd_isnailed;	/* rel is nailed in cache */
 	bool		rd_isvalid;		/* relcache entry is valid */
 	char		rd_indexvalid;	/* state of rd_indexlist: 0 = not valid, 1 =
@@ -355,9 +356,18 @@ typedef struct StdRdOptions
  * Beware of multiple eval of argument
  */
 #define RELATION_IS_LOCAL(relation) \
-	((relation)->rd_istemp || \
+	((relation)->rd_islocaltemp || \
 	 (relation)->rd_createSubid != InvalidSubTransactionId)
 
+/*
+ * RELATION_IS_OTHER_TEMP
+ *		Test for a temporary relation that belongs to some other session.
+ *
+ * Beware of multiple eval of argument
+ */
+#define RELATION_IS_OTHER_TEMP(relation) \
+	((relation)->rd_istemp && !(relation)->rd_islocaltemp)
+
 /* routines in utils/cache/relcache.c */
 extern void RelationIncrementReferenceCount(Relation rel);
 extern void RelationDecrementReferenceCount(Relation rel);