On 11/8/2025 20:15, Greg Sabino Mullane wrote:
I'm not convinced this is an improvement from someone just coming in to
this part of the code, especially given (for example) the comment right
above it:
* Determine if the inner table can duplicate outer rows. We must
* bypass the unique rel cache here since we're possibly using aThanks for
your feedback.
I made some minor adjustments to the comments to make the code more
consistent. Sure, rrel and krel don't seem like the best solution - I
guess natives could find less wordy synonyms than just dumb
'keeping_rel' and 'removing_rel'. But it is simpler to track which
relation and RowMark should be removed.
--
regards, Andrei Lepikhov
From 749c86bea70bed0d6b91fd656627b864e74369d3 Mon Sep 17 00:00:00 2001
From: "Andrei V. Lepikhov" <lepi...@gmail.com>
Date: Wed, 23 Jul 2025 13:46:02 +0200
Subject: [PATCH v1] Force RowMark Sanity Checking
The SJE feature eliminates incorrect RowMarks without introducing any potential
errors. This is due to a straightforward reason: the planned RowMark is 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. Additionally, it renames variables to make
similar errors more apparent in the future. Furthermore, it includes sanity
checks in setrefs.c on existing non-null RTE and RelOptInfo entries
for each RowMark.
---
src/backend/optimizer/plan/analyzejoins.c | 49 ++++++++++++-----------
src/backend/optimizer/plan/setrefs.c | 4 ++
2 files changed, 30 insertions(+), 23 deletions(-)
diff --git a/src/backend/optimizer/plan/analyzejoins.c
b/src/backend/optimizer/plan/analyzejoins.c
index 4d55c2ea591..df63f1699dc 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.
@@ -2142,21 +2145,21 @@ remove_self_joins_one_group(PlannerInfo *root, Relids
relids)
while ((r = bms_next_member(relids, r)) > 0)
{
- RelOptInfo *inner = root->simple_rel_array[r];
+ RelOptInfo *rrel = root->simple_rel_array[r];
k = r;
while ((k = bms_next_member(relids, k)) > 0)
{
Relids joinrelids = NULL;
- RelOptInfo *outer = root->simple_rel_array[k];
+ RelOptInfo *krel = root->simple_rel_array[k];
List *restrictlist;
List *selfjoinquals;
List *otherjoinquals;
ListCell *lc;
bool jinfo_check = true;
- PlanRowMark *omark = NULL;
- PlanRowMark *imark = NULL;
+ PlanRowMark *kmark = NULL;
+ PlanRowMark *rmark = NULL;
List *uclauses = NIL;
/* A sanity check: the relations have the same Oid. */
@@ -2194,21 +2197,21 @@ remove_self_joins_one_group(PlannerInfo *root, Relids
relids)
{
PlanRowMark *rowMark = (PlanRowMark *)
lfirst(lc);
- if (rowMark->rti == k)
+ if (rowMark->rti == r)
{
- Assert(imark == NULL);
- imark = rowMark;
+ Assert(rmark == NULL);
+ rmark = rowMark;
}
- else if (rowMark->rti == r)
+ else if (rowMark->rti == k)
{
- Assert(omark == NULL);
- omark = rowMark;
+ Assert(kmark == NULL);
+ kmark = rowMark;
}
- if (omark && imark)
+ if (kmark && rmark)
break;
}
- if (omark && imark && omark->markType !=
imark->markType)
+ if (kmark && rmark && kmark->markType !=
rmark->markType)
continue;
/*
@@ -2229,8 +2232,8 @@ remove_self_joins_one_group(PlannerInfo *root, Relids
relids)
* build_joinrel_restrictlist() routine.
*/
restrictlist = generate_join_implied_equalities(root,
joinrelids,
-
inner->relids,
-
outer, NULL);
+
rrel->relids,
+
krel, NULL);
if (restrictlist == NIL)
continue;
@@ -2240,7 +2243,7 @@ remove_self_joins_one_group(PlannerInfo *root, Relids
relids)
* otherjoinquals.
*/
split_selfjoin_quals(root, restrictlist, &selfjoinquals,
-
&otherjoinquals, inner->relid, outer->relid);
+
&otherjoinquals, rrel->relid, krel->relid);
Assert(list_length(restrictlist) ==
(list_length(selfjoinquals) +
list_length(otherjoinquals)));
@@ -2251,17 +2254,17 @@ remove_self_joins_one_group(PlannerInfo *root, Relids
relids)
* degenerate case works only if both sides have the
same clause.
* So doesn't matter which side to add.
*/
- selfjoinquals = list_concat(selfjoinquals,
outer->baserestrictinfo);
+ selfjoinquals = list_concat(selfjoinquals,
krel->baserestrictinfo);
/*
- * Determine if the inner table can duplicate outer
rows. We must
+ * 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 false negatives in the cache.
*/
- if (!innerrel_is_unique_ext(root, joinrelids,
inner->relids,
-
outer, JOIN_INNER, selfjoinquals,
+ if (!innerrel_is_unique_ext(root, joinrelids,
rrel->relids,
+
krel, JOIN_INNER, selfjoinquals,
list_length(otherjoinquals) == 0,
&uclauses))
continue;
@@ -2277,14 +2280,14 @@ remove_self_joins_one_group(PlannerInfo *root, Relids
relids)
* expressions, or we won't match the same row on each
side of the
* join.
*/
- if (!match_unique_clauses(root, inner, uclauses,
outer->relid))
+ if (!match_unique_clauses(root, rrel, uclauses,
krel->relid))
continue;
/*
- * We can remove either relation, so remove the inner
one in order
- * to simplify this loop.
+ * Remove rrel ReloptInfo from the planner structures
and the
+ * corresponding row mark.
*/
- remove_self_join_rel(root, omark, imark, outer, inner,
restrictlist);
+ remove_self_join_rel(root, kmark, rmark, krel, rrel,
restrictlist);
result = bms_add_member(result, r);
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));
--
2.50.1
