postgres.git / summary / log / commit / refs

commit    8951941fb8a4d7f239760d7a4cd8fcaeecde13e2
Author:   Alexander Korotkov <akorotkov@postgresql.org>
Date:     Sun Aug 24 00:34:22 2025 +0000
First released in: 18.0

    Improve RowMark handling during Self-Join Elimination
    
    The Self-Join Elimination SJE feature messes up keeping and removing RowMark's
    in remove_self_joins_one_group().  That didn't lead to user-level error,
    because the planned RowMark is only used to reference a rtable entry in later
    execution stages.  An RTE entry for keeping and removing relations is
    identical and refers to the same relation OID.
    
    To reduce confusion and prevent future issues, this commit cleans up the code
    and fixes the incorrect behaviour.  Furthermore, it includes sanity checks in
    setrefs.c on existing non-null RTE and RelOptInfo entries for each RowMark.
    
    Discussion: https://postgr.es/m/18c6bd6c-6d2a-419a-b0da-dfedef34b585%40gmail.com
    Author: Andrei Lepikhov <lepihov@gmail.com>
    Reviewed-by: Greg Sabino Mullane <htamfids@gmail.com>
    Backpatch-through: 18


 src/backend/optimizer/plan/analyzejoins.c | 9 ++++++---
 src/backend/optimizer/plan/setrefs.c      | 4 ++++
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/src/backend/optimizer/plan/analyzejoins.c b/src/backend/optimizer/plan/analyzejoins.c
index 5aa2e1e4535..4455a046d23 100644
--- a/src/backend/optimizer/plan/analyzejoins.c
+++ b/src/backend/optimizer/plan/analyzejoins.c
@@ -631,6 +631,7 @@ remove_leftjoinrel_from_query(PlannerInfo *root, int relid,
 	 * remove_join_clause_from_rels will touch it.)
 	 */
 	root->simple_rel_array[relid] = NULL;
+	root->simple_rte_array[relid] = NULL;
 
 	/* And nuke the RelOptInfo, just in case there's another access path */
 	pfree(rel);
@@ -1979,10 +1980,12 @@ remove_self_join_rel(PlannerInfo *root, PlanRowMark *kmark, PlanRowMark *rmark,
 	 * remove_join_clause_from_rels will touch it.)
 	 */
 	root->simple_rel_array[toRemove->relid] = NULL;
+	root->simple_rte_array[toRemove->relid] = NULL;
 
 	/* And nuke the RelOptInfo, just in case there's another access path. */
 	pfree(toRemove);
 
+
 	/*
 	 * Now repeat construction of attr_needed bits coming from all other
 	 * sources.
@@ -2194,12 +2197,12 @@ remove_self_joins_one_group(PlannerInfo *root, Relids relids)
 			{
 				PlanRowMark *rowMark = (PlanRowMark *) lfirst(lc);
 
-				if (rowMark->rti == k)
+				if (rowMark->rti == r)
 				{
 					Assert(rmark == NULL);
 					rmark = rowMark;
 				}
-				else if (rowMark->rti == r)
+				else if (rowMark->rti == k)
 				{
 					Assert(kmark == NULL);
 					kmark = rowMark;
@@ -2254,7 +2257,7 @@ remove_self_joins_one_group(PlannerInfo *root, Relids relids)
 			selfjoinquals = list_concat(selfjoinquals, krel->baserestrictinfo);
 
 			/*
-			 * Determine if the rrel can duplicate outer rows.  We must bypass
+			 * Determine if the rrel can duplicate outer rows. We must bypass
 			 * the unique rel cache here since we're possibly using a subset
 			 * of join quals. We can use 'force_cache' == true when all join
 			 * quals are self-join quals.  Otherwise, we could end up putting
diff --git a/src/backend/optimizer/plan/setrefs.c b/src/backend/optimizer/plan/setrefs.c
index 846e44186c3..d706546f332 100644
--- a/src/backend/optimizer/plan/setrefs.c
+++ b/src/backend/optimizer/plan/setrefs.c
@@ -307,6 +307,10 @@ set_plan_references(PlannerInfo *root, Plan *plan)
 		PlanRowMark *rc = lfirst_node(PlanRowMark, lc);
 		PlanRowMark *newrc;
 
+		/* sanity check on existing row marks */
+		Assert(root->simple_rel_array[rc->rti] != NULL &&
+			   root->simple_rte_array[rc->rti] != NULL);
+
 		/* flat copy is enough since all fields are scalars */
 		newrc = (PlanRowMark *) palloc(sizeof(PlanRowMark));
 		memcpy(newrc, rc, sizeof(PlanRowMark));


[parent: 8202b0e83d09]