Refactoring of visibility functions for global temp table tuples

Author: knizhnik

src/backend/access/heap/heapam_handler.c

@@ -226,7 +226,7 @@ heapam_tuple_satisfies_snapshot(Relation rel, TupleTableSlot *slot,
 	 * Caller should be holding pin, but not lock.
 	 */
 	LockBuffer(bslot->buffer, BUFFER_LOCK_SHARE);
-	
+
 	res = HeapTupleSatisfiesVisibility(rel, bslot->base.tuple, snapshot,
 									   bslot->buffer);
 	LockBuffer(bslot->buffer, BUFFER_LOCK_UNLOCK);

src/backend/access/heap/heapam_visibility.c

@@ -1682,7 +1682,7 @@ HeapTupleSatisfiesHistoricMVCC(HeapTuple htup, Snapshot snapshot,
 
 /*
  * TempTupleSatisfiesVisibility
- *		True iff global temp table tuple is visible for the given snapshot.
+ *		True iff global temp table tuple is visible for the current transaction.
  *
  * Temporary tables are visible only for current backend, so there is no need to
  * handle cases with tuples committed by other backends. We only need to exclude
@@ -1696,7 +1696,6 @@ TempTupleSatisfiesVisibility(HeapTuple htup, CommandId curcid, Buffer buffer)
 	TransactionId xmin;
 	TransactionId xmax;
 
-
 	Assert(ItemPointerIsValid(&htup->t_self));
 	Assert(htup->t_tableOid != InvalidOid);
 
@@ -1720,27 +1719,17 @@ TempTupleSatisfiesVisibility(HeapTuple htup, CommandId curcid, Buffer buffer)
 	if (HEAP_XMAX_IS_LOCKED_ONLY(tuple->t_infomask))	/* not deleter */
 		return true;
 
-	if (tuple->t_infomask & HEAP_XMAX_IS_MULTI)
-	{
-		xmax = HeapTupleGetUpdateXid(tuple);
-
-		/* updating subtransaction must have aborted */
-		if (IsReplicaTransactionAborted(xmax))
-			return true;
+	xmax = (tuple->t_infomask & HEAP_XMAX_IS_MULTI)
+	    ? HeapTupleGetUpdateXid(tuple)
+		: HeapTupleHeaderGetRawXmax(tuple);
 
-		return (HeapTupleHeaderGetCmax(tuple) >= curcid);
-	}
-	xmax = HeapTupleHeaderGetRawXmax(tuple);
-
-	/* deleting subtransaction must have aborted */
 	if (IsReplicaTransactionAborted(xmax))
-		return true;
+		return true; /* updating subtransaction aborted */
 
-	if (IsReplicaCurrentTransactionId(xmax))
-		return (HeapTupleHeaderGetCmax(tuple) >= curcid); /* deleted after scan started */
+	if (!IsReplicaCurrentTransactionId(xmax))
+		return false; /* updating transaction committed */
 
-	/* xmax transaction committed */
-	return false;
+	return (HeapTupleHeaderGetCmax(tuple) >= curcid);	/* updated after scan started */
 }
 
 

src/backend/access/transam/varsup.c

@@ -69,6 +69,10 @@ GetNewTransactionId(bool isSubXact)
 		return FullTransactionIdFromEpochAndXid(0, BootstrapTransactionId);
 	}
 
+	/* safety check, we should never get this far in a HS standby */
+	if (RecoveryInProgress())
+   	    elog(ERROR, "cannot assign TransactionIds during recovery");
+
 	LWLockAcquire(XidGenLock, LW_EXCLUSIVE);
 
 	full_xid = ShmemVariableCache->nextFullXid;