Change more places to be less trusting of RestrictInfo.is_pushed_down.

On further reflection, commit e5d83995e didn't go far enough: pretty much
everywhere in the planner that examines a clause's is_pushed_down flag
ought to be changed to use the more complicated behavior where we also
check the clause's required_relids.  Otherwise we could make incorrect
decisions about whether, say, a clause is safe to use as a hash clause.

Some (many?) of these places are safe as-is, either because they are
never reached while considering a parameterized path, or because there
are additional checks that would reject a pushed-down clause anyway.
However, it seems smarter to just code them all the same way rather
than rely on easily-broken reasoning of that sort.

In support of that, invent a new macro RINFO_IS_PUSHED_DOWN that should
be used in place of direct tests on the is_pushed_down flag.

Like the previous patch, back-patch to all supported branches.

Discussion: https://postgr.es/m/f8128b11-c5bf-3539-48cd-234178b2314d@proxel.se

1 files changed, 2 insertions, 10 deletions

diff --git a/src/backend/optimizer/util/restrictinfo.c b/src/backend/optimizer/util/restrictinfo.c
index fd66c1303db..d5652b0f728 100644
--- a/src/backend/optimizer/util/restrictinfo.c
+++ b/src/backend/optimizer/util/restrictinfo.c
@@ -371,7 +371,7 @@ extract_actual_clauses(List *restrictinfo_list,
  * extract_actual_join_clauses
  *
  * Extract bare clauses from 'restrictinfo_list', separating those that
- * syntactically match the join level from those that were pushed down.
+ * semantically match the join level from those that were pushed down.
  * Pseudoconstant clauses are excluded from the results.
  *
  * This is only used at outer joins, since for plain joins we don't care
@@ -392,15 +392,7 @@ extract_actual_join_clauses(List *restrictinfo_list,
 	{
 		RestrictInfo *rinfo = lfirst_node(RestrictInfo, l);
 
-		/*
-		 * We must check both is_pushed_down and required_relids, since an
-		 * outer-join clause that's been pushed down to some lower join level
-		 * via path parameterization will not be marked is_pushed_down;
-		 * nonetheless, it must be treated as a filter clause not a join
-		 * clause so far as the lower join level is concerned.
-		 */
-		if (rinfo->is_pushed_down ||
-			!bms_is_subset(rinfo->required_relids, joinrelids))
+		if (RINFO_IS_PUSHED_DOWN(rinfo, joinrelids))
 		{
 			if (!rinfo->pseudoconstant)
 				*otherquals = lappend(*otherquals, rinfo->clause);