From 34295b87fbbcbaf26280f53f006b20971dbad1f3 Mon Sep 17 00:00:00 2001
From: Alvaro Herrera <alvherre@alvh.no-ip.org>
Date: Wed, 1 Aug 2018 15:06:47 -0400
Subject: [PATCH] Fix per-tuple memory leak in partition tuple routing
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Some operations were being done in a longer-lived memory context,
causing intra-query leaks. It's not noticeable unless you're doing a
large COPY, but if you are, it eats enough memory to cause a problem.
Co-authored-by: Kohei KaiGai <kaigai@heterodb.com>
Co-authored-by: Amit Langote <Langote_Amit_f8@lab.ntt.co.jp>
Co-authored-by: Álvaro Herrera <alvherre@alvh.no-ip.org>
Discussion: https://postgr.es/m/CAOP8fzYtVFWZADq4c=KoTAqgDrHWfng+AnEPEZccyxqxPVbbWQ@mail.gmail.com
---
src/backend/executor/execPartition.c | 52 ++++++++++++++++++++--------
1 file changed, 38 insertions(+), 14 deletions(-)
diff --git a/src/backend/executor/execPartition.c b/src/backend/executor/execPartition.c
index 7a4665cc4ee..b61c0fcc300 100644
--- a/src/backend/executor/execPartition.c
+++ b/src/backend/executor/execPartition.c
@@ -193,9 +193,15 @@ ExecFindPartition(ResultRelInfo *resultRelInfo, PartitionDispatch *pd,
Datum values[PARTITION_MAX_KEYS];
bool isnull[PARTITION_MAX_KEYS];
Relation rel;
- PartitionDispatch parent;
+ PartitionDispatch dispatch;
ExprContext *ecxt = GetPerTupleExprContext(estate);
TupleTableSlot *ecxt_scantuple_old = ecxt->ecxt_scantuple;
+ TupleTableSlot *myslot = NULL;
+ MemoryContext oldcxt;
+ HeapTuple tuple;
+
+ /* use per-tuple context here to avoid leaking memory */
+ oldcxt = MemoryContextSwitchTo(GetPerTupleMemoryContext(estate));
/*
* First check the root table's partition constraint, if any. No point in
@@ -205,26 +211,24 @@ ExecFindPartition(ResultRelInfo *resultRelInfo, PartitionDispatch *pd,
ExecPartitionCheck(resultRelInfo, slot, estate, true);
/* start with the root partitioned table */
- parent = pd[0];
+ tuple = ExecFetchSlotTuple(slot);
+ dispatch = pd[0];
while (true)
{
PartitionDesc partdesc;
- TupleTableSlot *myslot = parent->tupslot;
- TupleConversionMap *map = parent->tupmap;
+ TupleConversionMap *map = dispatch->tupmap;
int cur_index = -1;
- rel = parent->reldesc;
+ rel = dispatch->reldesc;
partdesc = RelationGetPartitionDesc(rel);
/*
- * Convert the tuple to this parent's layout so that we can do certain
- * things we do below.
+ * Convert the tuple to this parent's layout, if different from the
+ * current relation.
*/
+ myslot = dispatch->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;
@@ -239,7 +243,7 @@ ExecFindPartition(ResultRelInfo *resultRelInfo, PartitionDispatch *pd,
* So update ecxt_scantuple accordingly.
*/
ecxt->ecxt_scantuple = slot;
- FormPartitionKeyDatum(parent, slot, estate, values, isnull);
+ FormPartitionKeyDatum(dispatch, slot, estate, values, isnull);
/*
* Nothing for get_partition_for_tuple() to do if there are no
@@ -263,15 +267,33 @@ ExecFindPartition(ResultRelInfo *resultRelInfo, PartitionDispatch *pd,
result = -1;
break;
}
- else if (parent->indexes[cur_index] >= 0)
+ else if (dispatch->indexes[cur_index] >= 0)
{
- result = parent->indexes[cur_index];
+ result = dispatch->indexes[cur_index];
+ /* success! */
break;
}
else
- parent = pd[-parent->indexes[cur_index]];
+ {
+ /* move down one level */
+ dispatch = pd[-dispatch->indexes[cur_index]];
+
+ /*
+ * Release the dedicated slot, if it was used. Create a copy of
+ * the tuple first, for the next iteration.
+ */
+ if (slot == myslot)
+ {
+ 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)
{
@@ -287,7 +309,9 @@ ExecFindPartition(ResultRelInfo *resultRelInfo, PartitionDispatch *pd,
val_desc ? errdetail("Partition key of the failing row contains %s.", val_desc) : 0));
}
+ MemoryContextSwitchTo(oldcxt);
ecxt->ecxt_scantuple = ecxt_scantuple_old;
+
return result;
}
--
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