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Commit7e5e8b3

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Fix crash when columns have been added to the end of a view.
expandRTE() supposed that an RTE_SUBQUERY subquery must have exactlyas many non-junk tlist items as the RTE has column aliases for it.This was true at the time the code was written, and is still true sofar as parse analysis is concerned --- but when the function is usedduring planning, the subquery might have appeared through insertionof a view that now has more columns than it did when the outer querywas parsed. This results in a core dump if, for instance, we haveto expand a whole-row Var that references the subquery.To avoid crashing, we can either stop expanding the RTE when we runout of aliases, or invent new aliases for the added columns. Whilethe latter might be more useful, the former is consistent with whatexpandRTE() does for composite-returning functions in the RTE_FUNCTIONcase, so it seems like we'd better do it that way.Per bug #14876 from Samuel Horwitz. This has been busted since commitff1ea21 allowed views to acquire more columns, so back-patch to allsupported branches.Discussion:https://postgr.es/m/20171026184035.1471.82810@wrigleys.postgresql.org
1 parentcf0331a commit7e5e8b3

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‎src/backend/parser/parse_relation.c

Lines changed: 11 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -2012,9 +2012,19 @@ expandRTE(RangeTblEntry *rte, int rtindex, int sublevels_up,
20122012
varattno++;
20132013
Assert(varattno==te->resno);
20142014

2015+
/*
2016+
* In scenarios where columns have been added to a view
2017+
* since the outer query was originally parsed, there can
2018+
* be more items in the subquery tlist than the outer
2019+
* query expects. We should ignore such extra column(s)
2020+
* --- compare the behavior for composite-returning
2021+
* functions, in the RTE_FUNCTION case below.
2022+
*/
2023+
if (!aliasp_item)
2024+
break;
2025+
20152026
if (colnames)
20162027
{
2017-
/* Assume there is one alias per target item */
20182028
char*label=strVal(lfirst(aliasp_item));
20192029

20202030
*colnames=lappend(*colnames,makeString(pstrdup(label)));

‎src/test/regress/expected/alter_table.out

Lines changed: 85 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -2156,6 +2156,91 @@ Foreign-key constraints:
21562156
"check_fk_presence_2_id_fkey" FOREIGN KEY (id) REFERENCES check_fk_presence_1(id)
21572157

21582158
DROP TABLE check_fk_presence_1, check_fk_presence_2;
2159+
-- check column addition within a view (bug #14876)
2160+
create table at_base_table(id int, stuff text);
2161+
insert into at_base_table values (23, 'skidoo');
2162+
create view at_view_1 as select * from at_base_table bt;
2163+
create view at_view_2 as select *, to_json(v1) as j from at_view_1 v1;
2164+
\d+ at_view_1
2165+
View "public.at_view_1"
2166+
Column | Type | Modifiers | Storage | Description
2167+
--------+---------+-----------+----------+-------------
2168+
id | integer | | plain |
2169+
stuff | text | | extended |
2170+
View definition:
2171+
SELECT bt.id,
2172+
bt.stuff
2173+
FROM at_base_table bt;
2174+
2175+
\d+ at_view_2
2176+
View "public.at_view_2"
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Column | Type | Modifiers | Storage | Description
2178+
--------+---------+-----------+----------+-------------
2179+
id | integer | | plain |
2180+
stuff | text | | extended |
2181+
j | json | | extended |
2182+
View definition:
2183+
SELECT v1.id,
2184+
v1.stuff,
2185+
to_json(v1.*) AS j
2186+
FROM at_view_1 v1;
2187+
2188+
explain (verbose, costs off) select * from at_view_2;
2189+
QUERY PLAN
2190+
----------------------------------------------------------
2191+
Seq Scan on public.at_base_table bt
2192+
Output: bt.id, bt.stuff, to_json(ROW(bt.id, bt.stuff))
2193+
(2 rows)
2194+
2195+
select * from at_view_2;
2196+
id | stuff | j
2197+
----+--------+----------------------------
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23 | skidoo | {"id":23,"stuff":"skidoo"}
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(1 row)
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create or replace view at_view_1 as select *, 2+2 as more from at_base_table bt;
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\d+ at_view_1
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View "public.at_view_1"
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Column | Type | Modifiers | Storage | Description
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--------+---------+-----------+----------+-------------
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id | integer | | plain |
2207+
stuff | text | | extended |
2208+
more | integer | | plain |
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View definition:
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SELECT bt.id,
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bt.stuff,
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2 + 2 AS more
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FROM at_base_table bt;
2214+
2215+
\d+ at_view_2
2216+
View "public.at_view_2"
2217+
Column | Type | Modifiers | Storage | Description
2218+
--------+---------+-----------+----------+-------------
2219+
id | integer | | plain |
2220+
stuff | text | | extended |
2221+
j | json | | extended |
2222+
View definition:
2223+
SELECT v1.id,
2224+
v1.stuff,
2225+
to_json(v1.*) AS j
2226+
FROM at_view_1 v1;
2227+
2228+
explain (verbose, costs off) select * from at_view_2;
2229+
QUERY PLAN
2230+
----------------------------------------------------------------
2231+
Seq Scan on public.at_base_table bt
2232+
Output: bt.id, bt.stuff, to_json(ROW(bt.id, bt.stuff, NULL))
2233+
(2 rows)
2234+
2235+
select * from at_view_2;
2236+
id | stuff | j
2237+
----+--------+----------------------------------------
2238+
23 | skidoo | {"id":23,"stuff":"skidoo","more":null}
2239+
(1 row)
2240+
2241+
drop view at_view_2;
2242+
drop view at_view_1;
2243+
drop table at_base_table;
21592244
--
21602245
-- lock levels
21612246
--

‎src/test/regress/sql/alter_table.sql

Lines changed: 20 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1402,6 +1402,26 @@ ROLLBACK;
14021402
\d check_fk_presence_2
14031403
DROPTABLE check_fk_presence_1, check_fk_presence_2;
14041404

1405+
-- check column addition within a view (bug #14876)
1406+
createtableat_base_table(idint, stufftext);
1407+
insert into at_base_tablevalues (23,'skidoo');
1408+
createviewat_view_1asselect*from at_base_table bt;
1409+
createviewat_view_2asselect*, to_json(v1)as jfrom at_view_1 v1;
1410+
\d+ at_view_1
1411+
\d+ at_view_2
1412+
explain (verbose, costs off)select*from at_view_2;
1413+
select*from at_view_2;
1414+
1415+
create or replaceviewat_view_1asselect*,2+2as morefrom at_base_table bt;
1416+
\d+ at_view_1
1417+
\d+ at_view_2
1418+
explain (verbose, costs off)select*from at_view_2;
1419+
select*from at_view_2;
1420+
1421+
dropview at_view_2;
1422+
dropview at_view_1;
1423+
droptable at_base_table;
1424+
14051425
--
14061426
-- lock levels
14071427
--

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