predlock-seqscan.patch

diff --git a/src/backend/executor/nodeSeqscan.c b/src/backend/executor/nodeSeqscan.c
index f356874..32a8f56 100644
--- a/src/backend/executor/nodeSeqscan.c
+++ b/src/backend/executor/nodeSeqscan.c
@@ -113,9 +113,13 @@ SeqRecheck(SeqScanState *node, TupleTableSlot *slot)
 TupleTableSlot *
 ExecSeqScan(SeqScanState *node)
 {
-	PredicateLockRelation(node->ss_currentRelation,
-						  node->ss_currentScanDesc->rs_snapshot);
-	node->ss_currentScanDesc->rs_relpredicatelocked = true;
+	if (!node->ss_currentScanDesc->rs_relpredicatelocked)
+	{
+		PredicateLockRelation(node->ss_currentRelation,
+							  node->ss_currentScanDesc->rs_snapshot);
+		node->ss_currentScanDesc->rs_relpredicatelocked = true;		
+	}
+	
 	return ExecScan((ScanState *) node,
 					(ExecScanAccessMtd) SeqNext,
 					(ExecScanRecheckMtd) SeqRecheck);