Fix an oversight in cbc127917 to handle MERGE correctly

ExecInitModifyTable() forgot to trim MERGE-related lists to exclude
entries for result relations pruned during initial pruning, so fix
that.

While at it, make the function's use of the pruned resultRelations
list, rather than ModifyTable.resultRelations, more consistent.

Reported-by: Alexander Lakhin <exclusion@gmail.com> (via sqlsmith)
Reviewed-by: Junwang Zhao <zhjwpku@gmail.com>
Discussion: https://postgr.es/m/e72c94d9-e5f9-4753-9bc1-69d72bd54b8a@gmail.com

1 files changed, 27 insertions, 8 deletions

diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index a15e7863b0d..b0fe50075ad 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -3643,14 +3643,15 @@ ExecMergeNotMatched(ModifyTableContext *context, ResultRelInfo *resultRelInfo,
 void
 ExecInitMerge(ModifyTableState *mtstate, EState *estate)
 {
-	ModifyTable *node = (ModifyTable *) mtstate->ps.plan;
+	List	   *mergeActionLists = mtstate->mt_mergeActionLists;
+	List	   *mergeJoinConditions = mtstate->mt_mergeJoinConditions;
 	ResultRelInfo *rootRelInfo = mtstate->rootResultRelInfo;
 	ResultRelInfo *resultRelInfo;
 	ExprContext *econtext;
 	ListCell   *lc;
 	int			i;
 
-	if (node->mergeActionLists == NIL)
+	if (mergeActionLists == NIL)
 		return;
 
 	mtstate->mt_merge_subcommands = 0;
@@ -3667,14 +3668,14 @@ ExecInitMerge(ModifyTableState *mtstate, EState *estate)
 	 * anything here, do so there too.
 	 */
 	i = 0;
-	foreach(lc, node->mergeActionLists)
+	foreach(lc, mergeActionLists)
 	{
 		List	   *mergeActionList = lfirst(lc);
 		Node	   *joinCondition;
 		TupleDesc	relationDesc;
 		ListCell   *l;
 
-		joinCondition = (Node *) list_nth(node->mergeJoinConditions, i);
+		joinCondition = (Node *) list_nth(mergeJoinConditions, i);
 		resultRelInfo = mtstate->resultRelInfo + i;
 		i++;
 		relationDesc = RelationGetDescr(resultRelInfo->ri_RelationDesc);
@@ -4475,6 +4476,8 @@ ExecInitModifyTable(ModifyTable *node, EState *estate, int eflags)
 	List	   *withCheckOptionLists = NIL;
 	List	   *returningLists = NIL;
 	List	   *updateColnosLists = NIL;
+	List	   *mergeActionLists = NIL;
+	List	   *mergeJoinConditions = NIL;
 	ResultRelInfo *resultRelInfo;
 	List	   *arowmarks;
 	ListCell   *l;
@@ -4518,6 +4521,18 @@ ExecInitModifyTable(ModifyTable *node, EState *estate, int eflags)
 
 				updateColnosLists = lappend(updateColnosLists, updateColnosList);
 			}
+			if (node->mergeActionLists)
+			{
+				List	   *mergeActionList = list_nth(node->mergeActionLists, i);
+
+				mergeActionLists = lappend(mergeActionLists, mergeActionList);
+			}
+			if (node->mergeJoinConditions)
+			{
+				List	   *mergeJoinCondition = list_nth(node->mergeJoinConditions, i);
+
+				mergeJoinConditions = lappend(mergeJoinConditions, mergeJoinCondition);
+			}
 		}
 		i++;
 	}
@@ -4544,6 +4559,8 @@ ExecInitModifyTable(ModifyTable *node, EState *estate, int eflags)
 	mtstate->mt_merge_updated = 0;
 	mtstate->mt_merge_deleted = 0;
 	mtstate->mt_updateColnosLists = updateColnosLists;
+	mtstate->mt_mergeActionLists = mergeActionLists;
+	mtstate->mt_mergeJoinConditions = mergeJoinConditions;
 
 	/*----------
 	 * Resolve the target relation. This is the same as:
@@ -4556,7 +4573,8 @@ ExecInitModifyTable(ModifyTable *node, EState *estate, int eflags)
 	 * If it's a partitioned or inherited table, the root partition or
 	 * appendrel RTE doesn't appear elsewhere in the plan and its RT index is
 	 * given explicitly in node->rootRelation.  Otherwise, the target relation
-	 * is the sole relation in the node->resultRelations list.
+	 * is the sole relation in the node->resultRelations list and, since it can
+	 * never be pruned, also in the resultRelations list constructed above.
 	 *----------
 	 */
 	if (node->rootRelation > 0)
@@ -4569,9 +4587,10 @@ ExecInitModifyTable(ModifyTable *node, EState *estate, int eflags)
 	else
 	{
 		Assert(list_length(node->resultRelations) == 1);
+		Assert(list_length(resultRelations) == 1);
 		mtstate->rootResultRelInfo = mtstate->resultRelInfo;
 		ExecInitResultRelation(estate, mtstate->resultRelInfo,
-							   linitial_int(node->resultRelations));
+							   linitial_int(resultRelations));
 	}
 
 	/* set up epqstate with dummy subplan data for the moment */
@@ -4599,8 +4618,8 @@ ExecInitModifyTable(ModifyTable *node, EState *estate, int eflags)
 		Index		resultRelation = lfirst_int(l);
 		List	   *mergeActions = NIL;
 
-		if (node->mergeActionLists)
-			mergeActions = list_nth(node->mergeActionLists, i);
+		if (mergeActionLists)
+			mergeActions = list_nth(mergeActionLists, i);
 
 		if (resultRelInfo != mtstate->rootResultRelInfo)
 		{