Fix missed step in removal of useless RESULT RTEs in the planner.

Commit 4be058fe9 forgot that the append_rel_list would already be
populated at the time we remove useless result RTEs, and it might contain
PlaceHolderVars that need to be adjusted like the ones in the main parse
tree.  This could lead to "no relation entry for relid N" failures later
on, when the planner tries to do something with an unadjusted PHV.

Per report from Tom Ellis.  Back-patch to v12 where the bug came in.

Discussion: https://postgr.es/m/20201205173056.GF30712@cloudinit-builder

diff --git a/src/backend/optimizer/prep/prepjointree.c b/src/backend/optimizer/prep/prepjointree.c
index 14521728c633bf86c16871c9eb77c95a8f8732a0..ce57dfa7cde729aa75591f938b9d24f3dd91de92 100644 (file)
--- a/src/backend/optimizer/prep/prepjointree.c
+++ b/src/backend/optimizer/prep/prepjointree.c
@@ -3256,6 +3256,7 @@ remove_result_refs(PlannerInfo *root, int varno, Node *newjtloc)
        subrelids = get_relids_in_jointree(newjtloc, false);
        Assert(!bms_is_empty(subrelids));
        substitute_phv_relids((Node *) root->parse, varno, subrelids);
+       fix_append_rel_relids(root->append_rel_list, varno, subrelids);
    }
 
    /*

diff --git a/src/test/regress/expected/join.out b/src/test/regress/expected/join.out
index a118041731989fe63654381fbc4d6d413fde4865..b0533a719554dde02cf5287c5bf63813f5472df3 100644 (file)
--- a/src/test/regress/expected/join.out
+++ b/src/test/regress/expected/join.out
@@ -3333,6 +3333,42 @@ select * from
  1 | 2 | 2
 (1 row)
 
+-- Test proper handling of appendrel PHVs during useless-RTE removal
+explain (costs off)
+select * from
+  (select 0 as z) as t1
+  left join
+  (select true as a) as t2
+  on true,
+  lateral (select true as b
+           union all
+           select a as b) as t3
+where b;
+              QUERY PLAN               
+---------------------------------------
+ Nested Loop
+   ->  Result
+   ->  Append
+         ->  Result
+         ->  Result
+               One-Time Filter: (true)
+(6 rows)
+
+select * from
+  (select 0 as z) as t1
+  left join
+  (select true as a) as t2
+  on true,
+  lateral (select true as b
+           union all
+           select a as b) as t3
+where b;
+ z | a | b 
+---+---+---
+ 0 | t | t
+ 0 | t | t
+(2 rows)
+
 --
 -- test inlining of immutable functions
 --

diff --git a/src/test/regress/sql/join.sql b/src/test/regress/sql/join.sql
index 4de24c19040154085b4a65d90e07a90cea83a907..00720b629a634d83df001540bf3612ee95afd42a 100644 (file)
--- a/src/test/regress/sql/join.sql
+++ b/src/test/regress/sql/join.sql
@@ -1056,6 +1056,28 @@ select * from
   (select 1 as x) ss1 left join (select 2 as y) ss2 on (true),
   lateral (select ss2.y as z limit 1) ss3;
 
+-- Test proper handling of appendrel PHVs during useless-RTE removal
+explain (costs off)
+select * from
+  (select 0 as z) as t1
+  left join
+  (select true as a) as t2
+  on true,
+  lateral (select true as b
+           union all
+           select a as b) as t3
+where b;
+
+select * from
+  (select 0 as z) as t1
+  left join
+  (select true as a) as t2
+  on true,
+  lateral (select true as b
+           union all
+           select a as b) as t3
+where b;
+
 --
 -- test inlining of immutable functions
 --