Remove some unnecessary fields from Plan trees.

In the wake of commit f2343653f, we no longer need some fields that
were used before to control executor lock acquisitions:

* PlannedStmt.nonleafResultRelations can go away entirely.

* partitioned_rels can go away from Append, MergeAppend, and ModifyTable.
However, ModifyTable still needs to know the RT index of the partition
root table if any, which was formerly kept in the first entry of that
list.  Add a new field "rootRelation" to remember that.  rootRelation is
partly redundant with nominalRelation, in that if it's set it will have
the same value as nominalRelation.  However, the latter field has a
different purpose so it seems best to keep them distinct.

Amit Langote, reviewed by David Rowley and Jesper Pedersen,
and whacked around a bit more by me

Discussion: https://postgr.es/m/468c85d9-540e-66a2-1dde-fec2b741e688@lab.ntt.co.jp

1 files changed, 3 insertions, 5 deletions

diff --git a/src/backend/optimizer/util/pathnode.c b/src/backend/optimizer/util/pathnode.c
index c5aaaf5c220..d50d86b252f 100644
--- a/src/backend/optimizer/util/pathnode.c
+++ b/src/backend/optimizer/util/pathnode.c
@@ -3292,9 +3292,7 @@ create_lockrows_path(PlannerInfo *root, RelOptInfo *rel,
  * 'operation' is the operation type
  * 'canSetTag' is true if we set the command tag/es_processed
  * 'nominalRelation' is the parent RT index for use of EXPLAIN
- * 'partitioned_rels' is an integer list of RT indexes of non-leaf tables in
- *		the partition tree, if this is an UPDATE/DELETE to a partitioned table.
- *		Otherwise NIL.
+ * 'rootRelation' is the partitioned table root RT index, or 0 if none
  * 'partColsUpdated' is true if any partitioning columns are being updated,
  *		either from the target relation or a descendent partitioned table.
  * 'resultRelations' is an integer list of actual RT indexes of target rel(s)
@@ -3309,7 +3307,7 @@ create_lockrows_path(PlannerInfo *root, RelOptInfo *rel,
 ModifyTablePath *
 create_modifytable_path(PlannerInfo *root, RelOptInfo *rel,
 						CmdType operation, bool canSetTag,
-						Index nominalRelation, List *partitioned_rels,
+						Index nominalRelation, Index rootRelation,
 						bool partColsUpdated,
 						List *resultRelations, List *subpaths,
 						List *subroots,
@@ -3377,7 +3375,7 @@ create_modifytable_path(PlannerInfo *root, RelOptInfo *rel,
 	pathnode->operation = operation;
 	pathnode->canSetTag = canSetTag;
 	pathnode->nominalRelation = nominalRelation;
-	pathnode->partitioned_rels = list_copy(partitioned_rels);
+	pathnode->rootRelation = rootRelation;
 	pathnode->partColsUpdated = partColsUpdated;
 	pathnode->resultRelations = resultRelations;
 	pathnode->subpaths = subpaths;