10000 Track nesting depth correctly when drilling down into RECORD Vars. · postgres/postgres@a374f6c · GitHub
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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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4 files changed

+123
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‎src/backend/parser/parse_target.c

Lines changed: 13 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -1471,7 +1471,8 @@ ExpandRowReference(ParseState *pstate, Node *expr,
14711471
* drill down to find the ultimate defining expression and attempt to infer
14721472
* the tupdesc from it. We ereport if we can't determine the tupdesc.
14731473
*
1474-
* levelsup is an extra offset to interpret the Var's varlevelsup correctly.
1474+
* levelsup is an extra offset to interpret the Var's varlevelsup correctly
1475+
* when recursing. Outside callers should pass zero.
14751476
*/
14761477
TupleDesc
14771478
expandRecordVariable(ParseState *pstate, Var *var, int levelsup)
@@ -1552,11 +1553,17 @@ expandRecordVariable(ParseState *pstate, Var *var, int levelsup)
15521553
/*
15531554
* Recurse into the sub-select to see what its Var refers
15541555
* to. We have to build an additional level of ParseState
1555-
* to keep in step with varlevelsup in the subselect.
1556+
* to keep in step with varlevelsup in the subselect;
1557+
* furthermore, the subquery RTE might be from an outer
1558+
* query level, in which case the ParseState for the
1559+
* subselect must have that outer level as parent.
15561560
*/
1557-
ParseState mypstate;
1561+
ParseState mypstate = {0};
1562+
Index levelsup;
15581563

1559-
MemSet(&mypstate, 0, sizeof(mypstate));
1564+
/* this loop must work, since GetRTEByRangeTablePosn did */
1565+
for (levelsup = 0; levelsup < netlevelsup; levelsup++)
1566+
pstate = pstate->parentParseState;
15601567
mypstate.parentParseState = pstate;
15611568
mypstate.p_rtable = rte->subquery->rtable;
15621569
/* don't bother filling the rest of the fake pstate */
@@ -1607,12 +1614,11 @@ expandRecordVariable(ParseState *pstate, Var *var, int levelsup)
16071614
* Recurse into the CTE to see what its Var refers to. We
16081615
* have to build an additional level of ParseState to keep
16091616
* in step with varlevelsup in the CTE; furthermore it
1610-
* could be an outer CTE.
1617+
* could be an outer CTE (compare SUBQUERY case above).
16111618
*/
1612-
ParseState mypstate;
1619+
ParseState mypstate = {0};
16131620
Index levelsup;
16141621

1615-
MemSet(&mypstate, 0, sizeof(mypstate));
16161622
/* this loop must work, since GetCTEForRTE did */
16171623
for (levelsup = 0;
16181624
levelsup < rte->ctelevelsup + netlevelsup;

‎src/backend/utils/adt/ruleutils.c

Lines changed: 22 additions & 15 deletions
Original file line numberDiff line numberDiff line change
@@ -7114,22 +7114,28 @@ get_name_for_var_field(Var *var, int fieldno,
71147114
* Recurse into the sub-select to see what its Var
71157115
* refers to. We have to build an additional level of
71167116
* namespace to keep in step with varlevelsup in the
7117-
* subselect.
7117+
* subselect; furthermore, the subquery RTE might be
7118+
* from an outer query level, in which case the
7119 8000 +
* namespace for the subselect must have that outer
7120+
* level as parent namespace.
71187121
*/
7122+
List *save_nslist = context->namespaces;
7123+
List *parent_namespaces;
71197124
deparse_namespace mydpns;
71207125
const char *result;
71217126

7127+
parent_namespaces = list_copy_tail(context->namespaces,
7128+
netlevelsup);
7129+
71227130
set_deparse_for_query(&mydpns, rte->subquery,
7123-
context->namespaces);
7131+
parent_namespaces);
71247132

7125-
context->namespaces = lcons(&mydpns,
7126-
context->namespaces);
7133+
context->namespaces = lcons(&mydpns, parent_namespaces);
71277134

71287135
result = get_name_for_var_field((Var *) expr, fieldno,
71297136
0, context);
71307137

7131-
context->namespaces =
7132-
list_delete_first(context->namespaces);
7138+
context->namespaces = save_nslist;
71337139

71347140
return result;
71357141
}
@@ -7221,29 +7227,30 @@ get_name_for_var_field(Var *var, int fieldno,
72217227
attnum);
72227228

72237229
if (ste == NULL || ste->resjunk)
7224-
elog(ERROR, "subquery %s does not have attribute %d",
7230+
elog(ERROR, "CTE %s does not have attribute %d",
72257231
rte->eref->aliasname, attnum);
72267232
expr = (Node *) ste->expr;
72277233
if (IsA(expr, Var))
72287234
{
72297235
/*
72307236
* Recurse into the CTE to see what its Var refers to.
72317237
* We have to build an additional level of namespace
7232-
* to keep in step with varlevelsup in the CTE.
7233-
* Furthermore it could be an outer CTE, so we may
7234-
* have to delete some levels of namespace.
7238+
* to keep in step with varlevelsup in the CTE;
7239+
* furthermore it could be an outer CTE (compare
7240+
* SUBQUERY case above).
72357241
*/
72367242
List *save_nslist = context->namespaces;
7237-
List *new_nslist;
7243+
List *parent_namespaces;
72387244
deparse_namespace mydpns;
72397245
const char *result;
72407246

7247+
parent_namespaces = list_copy_tail(context->namespaces,
7248+
ctelevelsup);
7249+
72417250
set_deparse_for_query(&mydpns, ctequery,
7242-
context->namespaces);
7251+
parent_namespaces);
72437252

7244-
new_nslist = list_copy_tail(context->namespaces,
7245-
ctelevelsup);
7246-
context->namespaces = lcons(&mydpns, new_nslist);
7253+
context->namespaces = lcons(&mydpns, parent_namespaces);
72477254

72487255
result = get_name_for_var_field((Var *) expr, fieldno,
72497256
0, context);

‎src/test/regress/expected/rowtypes.out

Lines changed: 63 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1093,6 +1093,69 @@ select r, r is null as isnull, r is not null as isnotnull from r;
10931093
(,) | t | f
10941094
(6 rows)
10951095

1096+
--
1097+
-- Check parsing of indirect references to composite values (bug #18077)
1098+
--
1099+
explain (verbose, costs off)
1100+
with cte(c) as (select row(1, 2)),
1101+
cte2(c) as (select * from cte)
1102+
select * from cte2 as t
1103+
where (select * from (select c as c1) s
1104+
where (select (c1).f1 > 0)) is not null;
1105+
QUERY PLAN
1106+
------------------------------------------
1107+
CTE Scan on cte2 t
1108+
Output: t.c
1109+
Filter: ((SubPlan 4) IS NOT NULL)
1110+
CTE cte
1111+
-> Result
1112+
Output: '(1,2)'::record
1113+
CTE cte2
1114+
-> CTE Scan on cte
1115+
Output: cte.c
1116+
SubPlan 4
1117+
-> Result
1118+
Output: t.c
1119+
One-Time Filter: $3
1120+
InitPlan 3 (returns $3)
1121+
-> Result
1122+
Output: ((t.c).f1 > 0)
1123+
(16 rows)
1124+
1125+
with cte(c) as (select row(1, 2)),
1126+
cte2(c) as (select * from cte)
1127+
select * from cte2 as t
1128+
where (select * from (select c as c1) s
1129+
where (select (c1).f1 > 0)) is not null;
1130+
c
1131+
-------
1132+
(1,2)
1133+
(1 row)
1134+
1135+
-- Also check deparsing of such cases
1136+
create view composite_v as
1137+
with cte(c) as (select row(1, 2)),
1138+
cte2(c) as (select * from cte)
1139+
select 1 as one from cte2 as t
1140+
where (select * from (select c as c1) s
1141+
where (select (c1).f1 > 0)) is not null;
1142+
select pg_get_viewdef('composite_v', true);
1143+
pg_get_viewdef
1144+
--------------------------------------------------------
1145+
WITH cte(c) AS ( +
1146+
SELECT ROW(1, 2) AS "row" +
1147+
), cte2(c) AS ( +
1148+
SELECT cte.c +
1149+
FROM cte +
1150+
) +
1151+
SELECT 1 AS one +
1152+
FROM cte2 t +
1153+
WHERE (( SELECT s.c1 +
1154+
FROM ( SELECT t.c AS c1) s +
1155+
WHERE ( SELECT (s.c1).f1 > 0))) IS NOT NULL;
1156+
(1 row)
1157+
1158+
drop view composite_v;
10961159
--
10971160
-- Tests for component access / FieldSelect
10981161
--

‎src/test/regress/sql/rowtypes.sql

Lines changed: 25 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -450,6 +450,31 @@ with r(a,b) as
450450
(null,row(1,2)), (null,row(null,null)), (null,null) )
451451
select r, r is null as isnull, r is not null as isnotnull from r;
452452

453+
--
454+
-- Check parsing of indirect references to composite values (bug #18077)
455+
--
456+
explain (verbose, costs off)
457+
with cte(c) as (select row(1, 2)),
458+
cte2(c) as (select * from cte)
459+
select * from cte2 as t
460+
where (select * from (select c as c1) s
461+
where (select (c1).f1 > 0)) is not null;
462+
463+
with cte(c) as (select row(1, 2)),
464+
cte2(c) as (select * from cte)
465+
select * from cte2 as t
466+
where (select * from (select c as c1) s
467+
where (select (c1).f1 > 0)) is not null;
468+
469+
-- Also check deparsing of such cases
470+
create view composite_v as
471+
with cte(c) as (select row(1, 2)),
472+
cte2(c) as (select * from cte)
473+
select 1 as one from cte2 as t
474+
where (select * from (select c as c1) s
475+
where (select (c1).f1 > 0)) is not null;
476+
select pg_get_viewdef('composite_v', true);
477+
drop view composite_v;
453478

454479
--
455480
-- Tests for component access / FieldSelect

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