v19-0002-mark_async_capable-subpath-should-match-subplan.patch

From 8eb27fc9f54e1ba59f15136e0872c3ed98804021 Mon Sep 17 00:00:00 2001
From: Alexander Korotkov <akorotkov@postgresql.org>
Date: Sun, 5 Apr 2026 03:58:23 +0300
Subject: [PATCH v19 2/6] mark_async_capable(): subpath should match subplan

mark_async_capable() believes that the path corresponds to the plan.  This is
not true when creating_[merge_]append_plan() inserts (Incremental)Sort node.
In this case,  mark_async_capable() can treat the Sort plan node as some other
node and crash.  Fix this by explicitly handling the (Incremental)Sort nodes
as not async-capable.  Also, move this check on top of the switch() as it
repeats in all the cases.

This is needed to make the MergeAppend node async-capable, which will be
implemented in the subsequent commits.

Discussion: https://postgr.es/m/59be194c5a409fb9fc9f2031581b8a44%40postgrespro.ru
Author: Alexander Pyhalov <a.pyhalov@postgrespro.ru>
Reviewed-by: Matheus Alcantara <matheusssilv97@gmail.com>
Reviewed-by: Alena Rybakina <a.rybakina@postgrespro.ru>
---
 src/backend/optimizer/plan/createplan.c | 29 +++++++------------------
 1 file changed, 8 insertions(+), 21 deletions(-)

diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index de6a183da79..7816558adec 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -1131,19 +1131,20 @@ create_join_plan(PlannerInfo *root, JoinPath *best_path)
 static bool
 mark_async_capable_plan(Plan *plan, Path *path)
 {
+	/*
+	 * If the generated plan node includes a gating Result node, a Sort node,
+	 * or an IncrementalSort node, we can't execute it asynchronously.
+	 */
+	if (IsA(plan, Result) || IsA(plan, Sort) ||
+		IsA(plan, IncrementalSort))
+		return false;
+
 	switch (nodeTag(path))
 	{
 		case T_SubqueryScanPath:
 			{
 				SubqueryScan *scan_plan = (SubqueryScan *) plan;
 
-				/*
-				 * If the generated plan node includes a gating Result node,
-				 * we can't execute it asynchronously.
-				 */
-				if (IsA(plan, Result))
-					return false;
-
 				/*
 				 * If a SubqueryScan node atop of an async-capable plan node
 				 * is deletable, consider it as async-capable.
@@ -1158,13 +1159,6 @@ mark_async_capable_plan(Plan *plan, Path *path)
 			{
 				FdwRoutine *fdwroutine = path->parent->fdwroutine;
 
-				/*
-				 * If the generated plan node includes a gating Result node,
-				 * we can't execute it asynchronously.
-				 */
-				if (IsA(plan, Result))
-					return false;
-
 				Assert(fdwroutine != NULL);
 				if (fdwroutine->IsForeignPathAsyncCapable != NULL &&
 					fdwroutine->IsForeignPathAsyncCapable((ForeignPath *) path))
@@ -1173,13 +1167,6 @@ mark_async_capable_plan(Plan *plan, Path *path)
 			}
 		case T_ProjectionPath:
 
-			/*
-			 * If the generated plan node includes a Result node for the
-			 * projection, we can't execute it asynchronously.
-			 */
-			if (IsA(plan, Result))
-				return false;
-
 			/*
 			 * create_projection_plan() would have pulled up the subplan, so
 			 * check the capability using the subpath.
-- 
2.39.5 (Apple Git-154)