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Track nesting depth correctly when drilling down into RECORD Vars.
expandRecordVariable() failed to adjust the parse nesting structure correctly when recursing to inspect an outer-level Var. This could result in assertion failures or core dumps in corner cases. Likewise, get_name_for_var_field() failed to adjust the deparse namespace stack correctly when recursing to inspect an outer-level Var. In this case the likely result was a "bogus varno" error while deparsing a view. Per bug #18077 from Jingzhou Fu. Back-patch to all supported branches. Richard Guo, with some adjustments by me Discussion: https://postgr.es/m/18077-b9db97c6e0ab45d8@postgresql.org
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-22
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4 files changed

+120
-22
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‎src/backend/parser/parse_target.c

Lines changed: 13 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -1472,7 +1472,8 @@ ExpandRowReference(ParseState *pstate, Node *expr,
14721472
* drill down to find the ultimate defining expression and attempt to infer
14731473
* the tupdesc from it. We ereport if we can't determine the tupdesc.
14741474
*
1475-
* levelsup is an extra offset to interpret the Var's varlevelsup correctly.
1475+
* levelsup is an extra offset to interpret the Var's varlevelsup correctly
1476+
* when recursing. Outside callers should pass zero.
14761477
*/
14771478
TupleDesc
14781479
expandRecordVariable(ParseState *pstate, Var *var, int levelsup)
@@ -1554,11 +1555,17 @@ expandRecordVariable(ParseState *pstate, Var *var, int levelsup)
15541555
/*
15551556
* Recurse into the sub-select to see what its Var refers
15561557
* to. We have to build an additional level of ParseState
1557-
* to keep in step with varlevelsup in the subselect.
1558+
* to keep in step with varlevelsup in the subselect;
1559+
* furthermore, the subquery RTE might be from an outer
1560+
* query level, in which case the ParseState for the
1561+
* subselect must have that outer level as parent.
15581562
*/
1559-
ParseState mypstate;
1563+
ParseState mypstate = {0};
1564+
Index levelsup;
15601565

1561-
MemSet(&mypstate, 0, sizeof(mypstate));
1566+
/* this loop must work, since GetRTEByRangeTablePosn did */
1567+
for (levelsup = 0; levelsup < netlevelsup; levelsup++)
1568+
pstate = pstate->parentParseState;
15621569
mypstate.parentParseState = pstate;
15631570
mypstate.p_rtable = rte->subquery->rtable;
15641571
/* don't bother filling the rest of the fake pstate */
@@ -1609,12 +1616,11 @@ expandRecordVariable(ParseState *pstate, Var *var, int levelsup)
16091616
* Recurse into the CTE to see what its Var refers to. We
16101617
* have to build an additional level of ParseState to keep
16111618
* in step with varlevelsup in the CTE; furthermore it
1612-
* could be an outer CTE.
1619+
* could be an outer CTE (compare SUBQUERY case above).
16131620
*/
1614-
ParseState mypstate;
1621+
ParseState mypstate = {0};
16151622
Index levelsup;
16161623

1617-
MemSet(&mypstate, 0, sizeof(mypstate));
16181624
/* this loop must work, since GetCTEForRTE did */
16191625
for (levelsup = 0;
16201626
levelsup < rte->ctelevelsup + netlevelsup;

‎src/backend/utils/adt/ruleutils.c

Lines changed: 22 additions & 15 deletions
Original file line numberDiff line numberDiff line change
@@ -7189,22 +7189,28 @@ get_name_for_var_field(Var *var, int fieldno,
71897189
* Recurse into the sub-select to see what its Var
71907190
* refers to. We have to build an additional level of
71917191
* namespace to keep in step with varlevelsup in the
7192-
* subselect.
7192+
* subselect; furthermore, the subquery RTE might be
7193+
* from an outer query level, in which case the
7194+
* namespace for the subselect must have that outer
7195+
* level as parent namespace.
71937196
*/
7197+
List *save_nslist = context->namespaces;
7198+
List *parent_namespaces;
71947199
deparse_namespace mydpns;
71957200
const char *result;
71967201

7202+
parent_namespaces = list_copy_tail(context->namespaces,
7203+
netlevelsup);
7204+
71977205
set_deparse_for_query(&mydpns, rte->subquery,
7198-
context->namespaces);
7206+
parent_namespaces);
71997207

7200-
context->namespaces = lcons(&mydpns,
7201-
context->namespaces);
7208+
context->namespaces = lcons(&mydpns, parent_namespaces);
72027209

72037210
result = get_name_for_var_field((Var *) expr, fieldno,
72047211
0, context);
72057212

7206-
context->namespaces =
7207-
list_delete_first(context->namespaces);
7213+
context->namespaces = save_nslist;
72087214

72097215
return result;
72107216
}
@@ -7296,29 +7302,30 @@ get_name_for_var_field(Var *var, int fieldno,
72967302
attnum);
72977303

72987304
if (ste == NULL || ste->resjunk)
7299-
elog(ERROR, "subquery %s does not have attribute %d",
7305+
elog(ERROR, "CTE %s does not have attribute %d",
73007306
rte->eref->aliasname, attnum);
73017307
expr = (Node *) ste->expr;
73027308
if (IsA(expr, Var))
73037309
{
73047310
/*
73057311
* Recurse into the CTE to see what its Var refers to.
73067312
* We have to build an additional level of namespace
7307-
* to keep in step with varlevelsup in the CTE.
7308-
* Furthermore it could be an outer CTE, so we may
7309-
* have to delete some levels of namespace.
7313+
* to keep in step with varlevelsup in the CTE;
7314+
* furthermore it could be an outer CTE (compare
7315+
* SUBQUERY case above).
73107316
*/
73117317
List *save_nslist = context->namespaces;
7312-
List *new_nslist;
7318+
List *parent_namespaces;
73137319
deparse_namespace mydpns;
73147320
const char *result;
73157321

7322+
parent_namespaces = list_copy_tail(context->namespaces,
7323+
ctelevelsup);
7324+
73167325
set_deparse_for_query(&mydpns, ctequery,
7317-
context->namespaces);
7326+
parent_namespaces);
73187327

7319-
new_nslist = list_copy_tail(context->namespaces,
7320-
ctelevelsup);
7321-
context->namespaces = lcons(&mydpns, new_nslist);
7328+
context->namespaces = lcons(&mydpns, parent_namespaces);
73227329

73237330
result = get_name_for_var_field((Var *) expr, fieldno,
73247331
0, context);

‎src/test/regress/expected/rowtypes.out

Lines changed: 60 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1203,6 +1203,66 @@ select r, r is null as isnull, r is not null as isnotnull from r;
12031203
(,) | t | f
12041204
(6 rows)
12051205

1206+
--
1207+
-- Check parsing of indirect references to composite values (bug #18077)
1208+
--
1209+
explain (verbose, costs off)
1210+
with cte(c) as materialized (select row(1, 2)),
1211+
cte2(c) as (select * from cte)
1212+
select * from cte2 as t
1213+
where (select * from (select c as c1) s
1214+
where (select (c1).f1 > 0)) is not null;
1215+
QUERY PLAN
1216+
--------------------------------------------
1217+
CTE Scan on cte
1218+
Output: cte.c
1219+
Filter: ((SubPlan 3) IS NOT NULL)
1220+
CTE cte
1221+
-> Result
1222+
Output: '(1,2)'::record
1223+
SubPlan 3
1224+
-> Result
1225+
Output: cte.c
1226+
One-Time Filter: $2
1227+
InitPlan 2 (returns $2)
1228+
-> Result
1229+
Output: ((cte.c).f1 > 0)
1230+
(13 rows)
1231+
1232+
with cte(c) as materialized (select row(1, 2)),
1233+
cte2(c) as (select * from cte)
1234+
select * from cte2 as t
1235+
where (select * from (select c as c1) s
1236+
where (select (c1).f1 > 0)) is not null;
1237+
c
1238+
-------
1239+
(1,2)
1240+
(1 row)
1241+
1242+
-- Also check deparsing of such cases
1243+
create view composite_v as
1244+
with cte(c) as materialized (select row(1, 2)),
1245+
cte2(c) as (select * from cte)
1246+
select 1 as one from cte2 as t
1247+
where (select * from (select c as c1) s
1248+
where (select (c1).f1 > 0)) is not null;
1249+
select pg_get_viewdef('composite_v', true);
1250+
pg_get_viewdef
1251+
--------------------------------------------------------
1252+
WITH cte(c) AS MATERIALIZED ( +
1253+
SELECT ROW(1, 2) AS "row" +
1254+
), cte2(c) AS ( +
1255+
SELECT cte.c +
1256+
FROM cte +
1257+
) +
1258+
SELECT 1 AS one +
1259+
FROM cte2 t +
1260+
WHERE (( SELECT s.c1 +
1261+
FROM ( SELECT t.c AS c1) s +
1262+
WHERE ( SELECT (s.c1).f1 > 0))) IS NOT NULL;
1263+
(1 row)
1264+
1265+
drop view composite_v;
12061266
--
12071267
-- Tests for component access / FieldSelect
12081268
--

‎src/test/regress/sql/rowtypes.sql

Lines changed: 25 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -483,6 +483,31 @@ with r(a,b) as materialized
483483
(null,row(1,2)), (null,row(null,null)), (null,null) )
484484
select r, r is null as isnull, r is not null as isnotnull from r;
485485

486+
--
487+
-- Check parsing of indirect references to composite values (bug #18077)
488+
--
489+
explain (verbose, costs off)
490+
with cte(c) as materialized (select row(1, 2)),
491+
cte2(c) as (select * from cte)
492+
select * from cte2 as t
493+
where (select * from (select c as c1) s
494+
where (select (c1).f1 > 0)) is not null;
495+
496+
with cte(c) as materialized (select row(1, 2)),
497+
cte2(c) as (select * from cte)
498+
select * from cte2 as t
499+
where (select * from (select c as c1) s
500+
where (select (c1).f1 > 0)) is not null;
501+
502+
-- Also check deparsing of such cases
503+
create view composite_v as
504+
with cte(c) as materialized (select row(1, 2)),
505+
cte2(c) as (select * from cte)
506+
select 1 as one from cte2 as t
507+
where (select * from (select c as c1) s
508+
where (select (c1).f1 > 0)) is not null;
509+
select pg_get_viewdef('composite_v', true);
510+
drop view composite_v;
486511

487512
--
488513
-- Tests for component access / FieldSelect

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