Fix 'negative bitmapset member' error

When removing a useless join, we'd remove PHVs that are not used at join
partner rels or above the join.  A PHV that references the join's relid
in ph_eval_at is logically "above" the join and thus should not be
removed.  We have the following check for that:

    !bms_is_member(ojrelid, phinfo->ph_eval_at)

However, in the case of SJE removing a useless inner join, 'ojrelid' is
set to -1, which would trigger the "negative bitmapset member not
allowed" error in bms_is_member().

Fix it by skipping examining ojrelid for inner joins in this check.

Reported-by: Zuming Jiang
Bug: #18260
Discussion: https://postgr.es/m/18260-1b6a0c4ae311b837%40postgresql.org
Author: Richard Guo
Reviewed-by: Andrei Lepikhov

src/backend/optimizer/plan/analyzejoins.c

@@ -456,7 +456,7 @@ remove_rel_from_query(PlannerInfo *root, RelOptInfo *rel,
 		Assert(sjinfo == NULL || !bms_is_member(relid, phinfo->ph_lateral));
 		if (bms_is_subset(phinfo->ph_needed, joinrelids) &&
 			bms_is_member(relid, phinfo->ph_eval_at) &&
-			!bms_is_member(ojrelid, phinfo->ph_eval_at))
+			(sjinfo == NULL || !bms_is_member(ojrelid, phinfo->ph_eval_at)))
 		{
 			root->placeholder_list = foreach_delete_current(root->placeholder_list,
 															l);

src/test/regress/expected/join.out

@@ -6821,6 +6821,26 @@ on true;
                            Filter: (id IS NOT NULL)
 (8 rows)
 
+-- Check that SJE removes the whole PHVs correctly
+explain (verbose, costs off)
+select 1 from emp1 t1 left join
+    ((select 1 as x, * from emp1 t2) s1 inner join
+        (select * from emp1 t3) s2 on s1.id = s2.id)
+    on true
+where s1.x = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Nested Loop
+   Output: 1
+   ->  Seq Scan on public.emp1 t1
+         Output: t1.id, t1.code
+   ->  Materialize
+         Output: t3.id
+         ->  Seq Scan on public.emp1 t3
+               Output: t3.id
+               Filter: ((t3.id IS NOT NULL) AND (1 = 1))
+(9 rows)
+
 -- Check that PHVs do not impose any constraints on removing self joins
 explain (verbose, costs off)
 select * from emp1 t1 join emp1 t2 on t1.id = t2.id left join

src/test/regress/sql/join.sql

@@ -2600,6 +2600,14 @@ select * from emp1 t1 left join
         on true)
 on true;
 
+-- Check that SJE removes the whole PHVs correctly
+explain (verbose, costs off)
+select 1 from emp1 t1 left join
+    ((select 1 as x, * from emp1 t2) s1 inner join
+        (select * from emp1 t3) s2 on s1.id = s2.id)
+    on true
+where s1.x = 1;
+
 -- Check that PHVs do not impose any constraints on removing self joins
 explain (verbose, costs off)
 select * from emp1 t1 join emp1 t2 on t1.id = t2.id left join