From 7e5e8b36d47891c1ffa9f6c592f02be850684d68 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Fri, 27 Oct 2017 17:10:21 -0400 Subject: [PATCH] Fix crash when columns have been added to the end of a view. expandRTE() supposed that an RTE_SUBQUERY subquery must have exactly as 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 so far as parse analysis is concerned --- but when the function is used during planning, the subquery might have appeared through insertion of a view that now has more columns than it did when the outer query was parsed. This results in a core dump if, for instance, we have to expand a whole-row Var that references the subquery. To avoid crashing, we can either stop expanding the RTE when we run out of aliases, or invent new aliases for the added columns. While the latter might be more useful, the former is consistent with what expandRTE() does for composite-returning functions in the RTE_FUNCTION case, so it seems like we'd better do it that way. Per bug #14876 from Samuel Horwitz. This has been busted since commit ff1ea2173 allowed views to acquire more columns, so back-patch to all supported branches. Discussion: https://postgr.es/m/20171026184035.1471.82810@wrigleys.postgresql.org --- src/backend/parser/parse_relation.c | 12 +++- src/test/regress/expected/alter_table.out | 85 +++++++++++++++++++++++ src/test/regress/sql/alter_table.sql | 20 ++++++ 3 files changed, 116 insertions(+), 1 deletion(-) diff --git a/src/backend/parser/parse_relation.c b/src/backend/parser/parse_relation.c index c51fd81b63..f4542b099e 100644 --- a/src/backend/parser/parse_relation.c +++ b/src/backend/parser/parse_relation.c @@ -2012,9 +2012,19 @@ expandRTE(RangeTblEntry *rte, int rtindex, int sublevels_up, varattno++; Assert(varattno == te->resno); + /* + * In scenarios where columns have been added to a view + * since the outer query was originally parsed, there can + * be more items in the subquery tlist than the outer + * query expects. We should ignore such extra column(s) + * --- compare the behavior for composite-returning + * functions, in the RTE_FUNCTION case below. + */ + if (!aliasp_item) + break; + if (colnames) { - /* Assume there is one alias per target item */ char *label = strVal(lfirst(aliasp_item)); *colnames = lappend(*colnames, makeString(pstrdup(label))); diff --git a/src/test/regress/expected/alter_table.out b/src/test/regress/expected/alter_table.out index 5283a99b47..06a8e16fae 100644 --- a/src/test/regress/expected/alter_table.out +++ b/src/test/regress/expected/alter_table.out @@ -2156,6 +2156,91 @@ Foreign-key constraints: "check_fk_presence_2_id_fkey" FOREIGN KEY (id) REFERENCES check_fk_presence_1(id) DROP TABLE check_fk_presence_1, check_fk_presence_2; +-- check column addition within a view (bug #14876) +create table at_base_table(id int, stuff text); +insert into at_base_table values (23, 'skidoo'); +create view at_view_1 as select * from at_base_table bt; +create view at_view_2 as select *, to_json(v1) as j from at_view_1 v1; +\d+ at_view_1 + View "public.at_view_1" + Column | Type | Modifiers | Storage | Description +--------+---------+-----------+----------+------------- + id | integer | | plain | + stuff | text | | extended | +View definition: + SELECT bt.id, + bt.stuff + FROM at_base_table bt; + +\d+ at_view_2 + View "public.at_view_2" + Column | Type | Modifiers | Storage | Description +--------+---------+-----------+----------+------------- + id | integer | | plain | + stuff | text | | extended | + j | json | | extended | +View definition: + SELECT v1.id, + v1.stuff, + to_json(v1.*) AS j + FROM at_view_1 v1; + +explain (verbose, costs off) select * from at_view_2; + QUERY PLAN +---------------------------------------------------------- + Seq Scan on public.at_base_table bt + Output: bt.id, bt.stuff, to_json(ROW(bt.id, bt.stuff)) +(2 rows) + +select * from at_view_2; + id | stuff | j +----+--------+---------------------------- + 23 | skidoo | {"id":23,"stuff":"skidoo"} +(1 row) + +create or replace view at_view_1 as select *, 2+2 as more from at_base_table bt; +\d+ at_view_1 + View "public.at_view_1" + Column | Type | Modifiers | Storage | Description +--------+---------+-----------+----------+------------- + id | integer | | plain | + stuff | text | | extended | + more | integer | | plain | +View definition: + SELECT bt.id, + bt.stuff, + 2 + 2 AS more + FROM at_base_table bt; + +\d+ at_view_2 + View "public.at_view_2" + Column | Type | Modifiers | Storage | Description +--------+---------+-----------+----------+------------- + id | integer | | plain | + stuff | text | | extended | + j | json | | extended | +View definition: + SELECT v1.id, + v1.stuff, + to_json(v1.*) AS j + FROM at_view_1 v1; + +explain (verbose, costs off) select * from at_view_2; + QUERY PLAN +---------------------------------------------------------------- + Seq Scan on public.at_base_table bt + Output: bt.id, bt.stuff, to_json(ROW(bt.id, bt.stuff, NULL)) +(2 rows) + +select * from at_view_2; + id | stuff | j +----+--------+---------------------------------------- + 23 | skidoo | {"id":23,"stuff":"skidoo","more":null} +(1 row) + +drop view at_view_2; +drop view at_view_1; +drop table at_base_table; -- -- lock levels -- diff --git a/src/test/regress/sql/alter_table.sql b/src/test/regress/sql/alter_table.sql index 71948abe1c..168d95ec4e 100644 --- a/src/test/regress/sql/alter_table.sql +++ b/src/test/regress/sql/alter_table.sql @@ -1402,6 +1402,26 @@ ROLLBACK; \d check_fk_presence_2 DROP TABLE check_fk_presence_1, check_fk_presence_2; +-- check column addition within a view (bug #14876) +create table at_base_table(id int, stuff text); +insert into at_base_table values (23, 'skidoo'); +create view at_view_1 as select * from at_base_table bt; +create view at_view_2 as select *, to_json(v1) as j from at_view_1 v1; +\d+ at_view_1 +\d+ at_view_2 +explain (verbose, costs off) select * from at_view_2; +select * from at_view_2; + +create or replace view at_view_1 as select *, 2+2 as more from at_base_table bt; +\d+ at_view_1 +\d+ at_view_2 +explain (verbose, costs off) select * from at_view_2; +select * from at_view_2; + +drop view at_view_2; +drop view at_view_1; +drop table at_base_table; + -- -- lock levels --