Some refactorting based on Craig Ringer review

Author: knizhnik

src/backend/access/gist/gistutil.c

@@ -1028,8 +1028,7 @@ gistGetFakeLSN(Relation rel)
 {
 	static XLogRecPtr counter = FirstNormalUnloggedLSN;
 
-	if (rel->rd_rel->relpersistence == RELPERSISTENCE_TEMP ||
-		rel->rd_rel->relpersistence == RELPERSISTENCE_SESSION)
+	if (RelationHasSessionScope(rel))
 	{
 		/*
 		 * Temporary relations are only accessible in our session, so a simple

src/backend/access/nbtree/nbtpage.c

@@ -764,7 +764,7 @@ _bt_getbuf(Relation rel, BlockNumber blkno, int access)
 		buf = ReadBuffer(rel, blkno);
 		LockBuffer(buf, access);
 		/* Session temporary relation may be not yet initialized for this backend. */
-		if (blkno == BTREE_METAPAGE && PageIsNew(BufferGetPage(buf)) && IsSessionRelationBackendId(rel->rd_backend))
+		if (blkno == BTREE_METAPAGE && GlobalTempRelationPageIsNotInitialized(rel, BufferGetPage(buf)))
 			_bt_initmetapage(BufferGetPage(buf), P_NONE, 0);
 		else
 			_bt_checkpage(rel, buf);

src/backend/commands/sequence.c

@@ -1183,7 +1183,7 @@ read_seq_tuple(Relation rel, Buffer *buf, HeapTuple seqdatatuple)
 	LockBuffer(*buf, BUFFER_LOCK_EXCLUSIVE);
 
 	page = BufferGetPage(*buf);
-	if (rel->rd_rel->relpersistence == RELPERSISTENCE_SESSION && PageIsNew(page))
+	if (GlobalTempRelationPageIsNotInitialized(rel, page))
 	{
 		/* Initialize sequence for global temporary tables */
 		Datum		value[SEQ_COL_LASTCOL] = {0};

src/backend/commands/tablecmds.c

@@ -586,8 +586,7 @@ DefineRelation(CreateStmt *stmt, char relkind, Oid ownerId,
 	 * Check consistency of arguments
 	 */
 	if (stmt->oncommit != ONCOMMIT_NOOP
-		&& stmt->relation->relpersistence != RELPERSISTENCE_TEMP
-		&& stmt->relation->relpersistence != RELPERSISTENCE_SESSION)
+		&& !IsLocalRelpersistence(stmt->relation->relpersistence))
 		ereport(ERROR,
 				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
 				 errmsg("ON COMMIT can only be used on temporary tables")));

src/backend/postmaster/autovacuum.c

@@ -2069,8 +2069,7 @@ do_autovacuum(void)
 		 * Check if it is a temp table (presumably, of some other backend's).
 		 * We cannot safely process other backends' temp tables.
 		 */
-		if (classForm->relpersistence == RELPERSISTENCE_TEMP ||
-			classForm->relpersistence == RELPERSISTENCE_SESSION)
+		if (IsLocalRelpersistence(classForm->relpersistence))
 		{
 			/*
 			 * We just ignore it if the owning backend is still active and
@@ -2155,8 +2154,7 @@ do_autovacuum(void)
 		/*
 		 * We cannot safely process other backends' temp tables, so skip 'em.
 		 */
-		if (classForm->relpersistence == RELPERSISTENCE_TEMP ||
-			classForm->relpersistence == RELPERSISTENCE_SESSION)
+		if (IsLocalRelpersistence(classForm->relpersistence))
 			continue;
 
 		relid = classForm->oid;

src/include/storage/bufpage.h

@@ -228,6 +228,13 @@ typedef PageHeaderData *PageHeader;
  */
 #define PageIsNew(page) (((PageHeader) (page))->pd_upper == 0)
 
+/*
+ * Page of temporary relation is not initialized
+ */
+#define GlobalTempRelationPageIsNotInitialized(rel, page) \
+	((rel)->rd_rel->relpersistence == RELPERSISTENCE_SESSION && PageIsNew(page))
+
+
 /*
  * PageGetItemId
  *		Returns an item identifier of a page.

src/include/utils/rel.h

@@ -328,6 +328,17 @@ typedef struct StdRdOptions
 	((relation)->rd_options ? \
 	 ((StdRdOptions *) (relation)->rd_options)->parallel_workers : (defaultpw))
 
+/*
+ * Relation persistence is either TEMP either SESSION
+ */
+#define IsLocalRelpersistence(relpersistence) \
+	((relpersistence) == RELPERSISTENCE_TEMP || (relpersistence) == RELPERSISTENCE_SESSION)
+
+/*
+ * Relation is either global either local temp table
+ */
+#define RelationHasSessionScope(relation) \
+	IsLocalRelpersistence(((relation)->rd_rel->relpersistence))
 
 /*
  * ViewOptions
@@ -524,7 +535,7 @@ typedef struct ViewOptions
  *		True if relation's pages are stored in local buffers.
  */
 #define RelationUsesLocalBuffers(relation) \
-	((relation)->rd_rel->relpersistence == RELPERSISTENCE_TEMP)
+	RelationHasSessionScope(relation)
 
 /*
  * RELATION_IS_LOCAL