From 8c42a8dcab7e2f835eff5c001d9be2829301429d Mon Sep 17 00:00:00 2001
From: amit <amitlangote09@gmail.com>
Date: Tue, 24 Jul 2018 15:11:25 +0900
Subject: [PATCH v1] Use per-tuple memory in ExecFindPartition

---
 src/backend/executor/execPartition.c | 38 ++++++++++++++++++++++++++++++++----
 1 file changed, 34 insertions(+), 4 deletions(-)

diff --git a/src/backend/executor/execPartition.c b/src/backend/executor/execPartition.c
index 7a4665cc4e..f5d9b1755a 100644
--- a/src/backend/executor/execPartition.c
+++ b/src/backend/executor/execPartition.c
@@ -196,6 +196,15 @@ ExecFindPartition(ResultRelInfo *resultRelInfo, PartitionDispatch *pd,
 	PartitionDispatch parent;
 	ExprContext *ecxt = GetPerTupleExprContext(estate);
 	TupleTableSlot *ecxt_scantuple_old = ecxt->ecxt_scantuple;
+	TupleTableSlot *myslot = NULL;
+	MemoryContext	oldcontext;
+	HeapTuple		tuple = ExecFetchSlotTuple(slot);
+
+	/*
+	 * Anything below that needs to allocate memory should use per-tuple
+	 * memory.
+	 */
+	oldcontext = MemoryContextSwitchTo(GetPerTupleMemoryContext(estate));
 
 	/*
 	 * First check the root table's partition constraint, if any.  No point in
@@ -209,7 +218,6 @@ ExecFindPartition(ResultRelInfo *resultRelInfo, PartitionDispatch *pd,
 	while (true)
 	{
 		PartitionDesc partdesc;
-		TupleTableSlot *myslot = parent->tupslot;
 		TupleConversionMap *map = parent->tupmap;
 		int			cur_index = -1;
 
@@ -220,11 +228,9 @@ ExecFindPartition(ResultRelInfo *resultRelInfo, PartitionDispatch *pd,
 		 * Convert the tuple to this parent's layout so that we can do certain
 		 * things we do below.
 		 */
+		myslot = parent->tupslot;
 		if (myslot != NULL && map != NULL)
 		{
-			HeapTuple	tuple = ExecFetchSlotTuple(slot);
-
-			ExecClearTuple(myslot);
 			tuple = do_convert_tuple(tuple, map);
 			ExecStoreTuple(tuple, myslot, InvalidBuffer, true);
 			slot = myslot;
@@ -269,9 +275,32 @@ ExecFindPartition(ResultRelInfo *resultRelInfo, PartitionDispatch *pd,
 			break;
 		}
 		else
+		{
 			parent = pd[-parent->indexes[cur_index]];
+
+			/*
+			 * If we used the dedicated slot, must call ExecClearTuple now
+			 * to release the tuple contained in it and set its
+			 * tts_shouldFree to false so that nobody attempts to release it
+			 * later.  We have to do that because the tuple uses per-tuple
+			 * memory.
+			 */
+			if (slot == myslot)
+			{
+				/*
+				 * Copy the tuple to be used for further routing before
+				 * clearing the slot itself.
+				 */
+				tuple = ExecCopySlotTuple(myslot);
+				ExecClearTuple(myslot);
+			}
+		}
 	}
 
+	/* Release the tuple in the lowest parent's dedicated slot. */
+	if (slot == myslot)
+		ExecClearTuple(myslot);
+
 	/* A partition was not found. */
 	if (result < 0)
 	{
@@ -287,6 +316,7 @@ ExecFindPartition(ResultRelInfo *resultRelInfo, PartitionDispatch *pd,
 				 val_desc ? errdetail("Partition key of the failing row contains %s.", val_desc) : 0));
 	}
 
+	MemoryContextSwitchTo(oldcontext);
 	ecxt->ecxt_scantuple = ecxt_scantuple_old;
 	return result;
 }
-- 
2.11.0