Ensure dummy paths have correct required_outer if rel is parameterized.

tglsfdc · tglsfdc · commit 98f8ffa18ebe · 2019-03-14T12:16:10.000-04:00
The assertions added by commits 34ea1ab et al found another problem: set_dummy_rel_pathlist and mark_dummy_rel were failing to label the dummy paths they create with the correct outer_relids, in case the relation is necessarily parameterized due to having lateral references in its tlist. It's likely that this has no user-visible consequences in production builds, at the moment; but still an assertion failure is a bad thing, so back-patch the fix. Per bug #15694 from Roman Zharkov (via Alexander Lakhin) and an independent report by Tushar Ahuja. Discussion: https://postgr.es/m/15694-74f2ca97e7044f7f@postgresql.org Discussion: https://postgr.es/m/7d72ab20-c725-3ce2-f99d-4e64dd8a0de6@enterprisedb.com
diff --git a/src/backend/optimizer/path/allpaths.c b/src/backend/optimizer/path/allpaths.c
@@ -1145,7 +1145,8 @@ set_dummy_rel_pathlist(RelOptInfo *rel)
 	/* Discard any pre-existing paths; no further need for them */
 	rel->pathlist = NIL;
 
-	add_path(rel, (Path *) create_append_path(rel, NIL, NULL));
+	add_path(rel, (Path *) create_append_path(rel, NIL,
+											  rel->lateral_relids));
 
 	/* Select cheapest path (pretty easy in this case...) */
 	set_cheapest(rel);
diff --git a/src/backend/optimizer/path/joinrels.c b/src/backend/optimizer/path/joinrels.c
@@ -1218,7 +1218,8 @@ mark_dummy_rel(RelOptInfo *rel)
 	rel->pathlist = NIL;
 
 	/* Set up the dummy path */
-	add_path(rel, (Path *) create_append_path(rel, NIL, NULL));
+	add_path(rel, (Path *) create_append_path(rel, NIL,
+											  rel->lateral_relids));
 
 	/* Set or update cheapest_total_path and related fields */
 	set_cheapest(rel);
diff --git a/src/test/regress/expected/join.out b/src/test/regress/expected/join.out
@@ -5091,6 +5091,37 @@ select * from
          Output: 3
 (11 rows)
 
+-- check dummy rels with lateral references (bug #15694)
+explain (verbose, costs off)
+select * from int8_tbl i8 left join lateral
+  (select *, i8.q2 from int4_tbl where false) ss on true;
+                  QUERY PLAN                  
+----------------------------------------------
+ Nested Loop Left Join
+   Output: i8.q1, i8.q2, int4_tbl.f1, (i8.q2)
+   ->  Seq Scan on public.int8_tbl i8
+         Output: i8.q1, i8.q2
+   ->  Result
+         Output: int4_tbl.f1, (i8.q2)
+         One-Time Filter: false
+         ->  Seq Scan on public.int4_tbl
+               Output: int4_tbl.f1, i8.q2
+(9 rows)
+
+explain (verbose, costs off)
+select * from int8_tbl i8 left join lateral
+  (select *, i8.q2 from int4_tbl i1, int4_tbl i2 where false) ss on true;
+               QUERY PLAN                
+-----------------------------------------
+ Nested Loop Left Join
+   Output: i8.q1, i8.q2, f1, f1, (i8.q2)
+   ->  Seq Scan on public.int8_tbl i8
+         Output: i8.q1, i8.q2
+   ->  Result
+         Output: f1, f1, i8.q2
+         One-Time Filter: false
+(7 rows)
+
 -- check handling of nested appendrels inside LATERAL
 select * from
   ((select 2 as v) union all (select 3 as v)) as q1
diff --git a/src/test/regress/sql/join.sql b/src/test/regress/sql/join.sql
@@ -1631,6 +1631,14 @@ select * from
     select * from (select 3 as z) z where z.z = x.x
   ) zz on zz.z = y.y;
 
+-- check dummy rels with lateral references (bug #15694)
+explain (verbose, costs off)
+select * from int8_tbl i8 left join lateral
+  (select *, i8.q2 from int4_tbl where false) ss on true;
+explain (verbose, costs off)
+select * from int8_tbl i8 left join lateral
+  (select *, i8.q2 from int4_tbl i1, int4_tbl i2 where false) ss on true;
+
 -- check handling of nested appendrels inside LATERAL
 select * from
   ((select 2 as v) union all (select 3 as v)) as q1
