Move partition_tuple_slot out of EState.

Commit 2ac3ef7a01df859c62d0a02333b646d65eaec5ff added a TupleTapleSlot
for partition tuple slot to EState (es_partition_tuple_slot) but it's
more logical to have it as part of ModifyTableState
(mt_partition_tuple_slot) and CopyState (partition_tuple_slot).

Discussion: http://postgr.es/m/1bd459d9-4c0c-197a-346e-e5e59e217d97@lab.ntt.co.jp

Amit Langote, per a gripe from me

2 files changed, 20 insertions, 9 deletions

diff --git a/src/backend/executor/execMain.c b/src/backend/executor/execMain.c
index 7e3c207018f..eb9b528c4e4 100644
--- a/src/backend/executor/execMain.c
+++ b/src/backend/executor/execMain.c
@@ -3012,6 +3012,9 @@ EvalPlanQualEnd(EPQState *epqstate)
  *		entry for every leaf partition (required to convert input tuple based
  *		on the root table's rowtype to a leaf partition's rowtype after tuple
  *		routing is done
+ * 'partition_tuple_slot' receives a standalone TupleTableSlot to be used
+ *		to manipulate any given leaf partition's rowtype after that partition
+ *		is chosen by tuple-routing.
  * 'num_parted' receives the number of partitioned tables in the partition
  *		tree (= the number of entries in the 'pd' output array)
  * 'num_partitions' receives the number of leaf partitions in the partition
@@ -3026,6 +3029,7 @@ ExecSetupPartitionTupleRouting(Relation rel,
 							   PartitionDispatch **pd,
 							   ResultRelInfo **partitions,
 							   TupleConversionMap ***tup_conv_maps,
+							   TupleTableSlot **partition_tuple_slot,
 							   int *num_parted, int *num_partitions)
 {
 	TupleDesc	tupDesc = RelationGetDescr(rel);
@@ -3043,6 +3047,14 @@ ExecSetupPartitionTupleRouting(Relation rel,
 	*tup_conv_maps = (TupleConversionMap **) palloc0(*num_partitions *
 										   sizeof(TupleConversionMap *));
 
+	/*
+	 * Initialize an empty slot that will be used to manipulate tuples of any
+	 * given partition's rowtype.  It is attached to the caller-specified node
+	 * (such as ModifyTableState) and released when the node finishes
+	 * processing.
+	 */
+	*partition_tuple_slot = MakeTupleTableSlot();
+
 	leaf_part_rri = *partitions;
 	i = 0;
 	foreach(cell, leaf_parts)
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index c7dd148944e..aa364707f8d 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -329,7 +329,7 @@ ExecInsert(ModifyTableState *mtstate,
 			 * Use the dedicated slot for that.
 			 */
 			oldslot = slot;
-			slot = estate->es_partition_tuple_slot;
+			slot = mtstate->mt_partition_tuple_slot;
 			Assert(slot != NULL);
 			ExecSetSlotDescriptor(slot, RelationGetDescr(partrel));
 			ExecStoreTuple(tuple, slot, InvalidBuffer, true);
@@ -1738,6 +1738,7 @@ ExecInitModifyTable(ModifyTable *node, EState *estate, int eflags)
 		PartitionDispatch  *partition_dispatch_info;
 		ResultRelInfo	   *partitions;
 		TupleConversionMap **partition_tupconv_maps;
+		TupleTableSlot	   *partition_tuple_slot;
 		int					num_parted,
 							num_partitions;
 
@@ -1745,21 +1746,15 @@ ExecInitModifyTable(ModifyTable *node, EState *estate, int eflags)
 									   &partition_dispatch_info,
 									   &partitions,
 									   &partition_tupconv_maps,
+									   &partition_tuple_slot,
 									   &num_parted, &num_partitions);
 		mtstate->mt_partition_dispatch_info = partition_dispatch_info;
 		mtstate->mt_num_dispatch = num_parted;
 		mtstate->mt_partitions = partitions;
 		mtstate->mt_num_partitions = num_partitions;
 		mtstate->mt_partition_tupconv_maps = partition_tupconv_maps;
-
-		/*
-		 * Initialize a dedicated slot to manipulate tuples of any given
-		 * partition's rowtype.
-		 */
-		estate->es_partition_tuple_slot = ExecInitExtraTupleSlot(estate);
+		mtstate->mt_partition_tuple_slot = partition_tuple_slot;
 	}
-	else
-		estate->es_partition_tuple_slot = NULL;
 
 	/*
 	 * Initialize any WITH CHECK OPTION constraints if needed.
@@ -2100,6 +2095,10 @@ ExecEndModifyTable(ModifyTableState *node)
 		heap_close(resultRelInfo->ri_RelationDesc, NoLock);
 	}
 
+	/* Release the standalone partition tuple descriptor, if any */
+	if (node->mt_partition_tuple_slot)
+		ExecDropSingleTupleTableSlot(node->mt_partition_tuple_slot);
+
 	/*
 	 * Free the exprcontext
 	 */