Revise child-to-root tuple conversion map management.

Store the tuple conversion map to convert a tuple from a child table's
format to the root format in a new ri_ChildToRootMap field in
ResultRelInfo. It is initialized if transition tuple capture for FOR
STATEMENT triggers or INSERT tuple routing on a partitioned table is
needed. Previously, ModifyTable kept the maps in the per-subplan
ModifyTableState->mt_per_subplan_tupconv_maps array, or when tuple
routing was used, in
ResultRelInfo->ri_Partitioninfo->pi_PartitionToRootMap. The new field
replaces both of those.

Now that the child-to-root tuple conversion map is always available in
ResultRelInfo (when needed), remove the TransitionCaptureState.tcs_map
field. The callers of Exec*Trigger() functions no longer need to set or
save it, which is much less confusing and bug-prone. Also, as a future
optimization, this will allow us to delay creating the map for a given
result relation until the relation is actually processed during
execution.

Author: Amit Langote
Discussion: https://www.postgresql.org/message-id/CA%2BHiwqHtCWLdK-LO%3DNEsvOdHx%2B7yv4mE_zYK0i3BH7dXb-wxog%40mail.gmail.com

1 files changed, 9 insertions, 14 deletions

diff --git a/src/backend/executor/execPartition.c b/src/backend/executor/execPartition.c
index 33d2c6f63de..08f91e59a7a 100644
--- a/src/backend/executor/execPartition.c
+++ b/src/backend/executor/execPartition.c
@@ -908,6 +908,15 @@ ExecInitPartitionInfo(ModifyTableState *mtstate, EState *estate,
 	}
 
 	/*
+	 * Also, if transition capture is required, store a map to convert tuples
+	 * from partition's rowtype to the root partition table's.
+	 */
+	if (mtstate->mt_transition_capture || mtstate->mt_oc_transition_capture)
+		leaf_part_rri->ri_ChildToRootMap =
+			convert_tuples_by_name(RelationGetDescr(leaf_part_rri->ri_RelationDesc),
+								   RelationGetDescr(leaf_part_rri->ri_PartitionRoot));
+
+	/*
 	 * Since we've just initialized this ResultRelInfo, it's not in any list
 	 * attached to the estate as yet.  Add it, so that it can be found later.
 	 *
@@ -977,20 +986,6 @@ ExecInitRoutingInfo(ModifyTableState *mtstate,
 		partrouteinfo->pi_PartitionTupleSlot = NULL;
 
 	/*
-	 * Also, if transition capture is required, store a map to convert tuples
-	 * from partition's rowtype to the root partition table's.
-	 */
-	if (mtstate &&
-		(mtstate->mt_transition_capture || mtstate->mt_oc_transition_capture))
-	{
-		partrouteinfo->pi_PartitionToRootMap =
-			convert_tuples_by_name(RelationGetDescr(partRelInfo->ri_RelationDesc),
-								   RelationGetDescr(partRelInfo->ri_PartitionRoot));
-	}
-	else
-		partrouteinfo->pi_PartitionToRootMap = NULL;
-
-	/*
 	 * If the partition is a foreign table, let the FDW init itself for
 	 * routing tuples to the partition.
 	 */