From b355be443b74d2749db00242d068fabc2df39f27 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Sun, 17 Feb 2019 12:37:32 -0500 Subject: [PATCH] Fix CREATE VIEW to allow zero-column views. We should logically have allowed this case when we allowed zero-column tables, but it was overlooked. Although this might be thought a feature addition, it's really a bug fix, because it was possible to create a zero-column view via the convert-table-to-view code path, and then you'd have a situation where dump/reload would fail. Hence, back-patch to all supported branches. Arrange the added test cases to provide coverage of the related pg_dump code paths (since these views will be dumped and reloaded during the pg_upgrade regression test). I also made them test the case where pg_dump has to postpone the view rule into post-data, which disturbingly had no regression coverage before. Report and patch by Ashutosh Sharma (test case by me) Discussion: https://postgr.es/m/CAE9k0PkmHdeSaeZt2ujnb_cKucmK3sDDceDzw7+d5UZoNJPYOg@mail.gmail.com --- src/backend/commands/view.c | 5 ----- src/test/regress/expected/create_view.out | 10 ++++++++++ src/test/regress/expected/rules.out | 8 ++++++++ src/test/regress/expected/sanity_check.out | 1 + src/test/regress/sql/create_view.sql | 12 ++++++++++++ 5 files changed, 31 insertions(+), 5 deletions(-) diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c index c55f6b0235a..615e191f4e7 100644 --- a/src/backend/commands/view.c +++ b/src/backend/commands/view.c @@ -111,11 +111,6 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace, } } - if (attrList == NIL) - ereport(ERROR, - (errcode(ERRCODE_INVALID_TABLE_DEFINITION), - errmsg("view must have at least one column"))); - /* * Look up, check permissions on, and lock the creation namespace; also * check for a preexisting view with the same name. This will also set diff --git a/src/test/regress/expected/create_view.out b/src/test/regress/expected/create_view.out index f909a3cefeb..cfac12492f5 100644 --- a/src/test/regress/expected/create_view.out +++ b/src/test/regress/expected/create_view.out @@ -20,6 +20,16 @@ COMMENT ON VIEW noview IS 'no view'; ERROR: relation "noview" does not exist COMMENT ON VIEW toyemp IS 'is a view'; COMMENT ON VIEW toyemp IS NULL; +-- These views are left around mainly to exercise special cases in pg_dump. +CREATE TABLE view_base_table (key int PRIMARY KEY, data varchar(20)); +CREATE VIEW key_dependent_view AS + SELECT * FROM view_base_table GROUP BY key; +ALTER TABLE view_base_table DROP CONSTRAINT view_base_table_pkey; -- fails +ERROR: cannot drop constraint view_base_table_pkey on table view_base_table because other objects depend on it +DETAIL: view key_dependent_view depends on constraint view_base_table_pkey on table view_base_table +HINT: Use DROP ... CASCADE to drop the dependent objects too. +CREATE VIEW key_dependent_view_no_cols AS + SELECT FROM view_base_table GROUP BY key HAVING length(data) > 0; -- -- CREATE OR REPLACE VIEW -- diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out index 99e01b9a254..92fd1446d51 100644 --- a/src/test/regress/expected/rules.out +++ b/src/test/regress/expected/rules.out @@ -1289,6 +1289,14 @@ iexit| SELECT ih.name, FROM ihighway ih, ramp r WHERE (ih.thepath ## r.thepath); +key_dependent_view| SELECT view_base_table.key, + view_base_table.data + FROM view_base_table + GROUP BY view_base_table.key; +key_dependent_view_no_cols| SELECT + FROM view_base_table + GROUP BY view_base_table.key + HAVING (length((view_base_table.data)::text) > 0); mvtest_tv| SELECT mvtest_t.type, sum(mvtest_t.amt) AS totamt FROM mvtest_t diff --git a/src/test/regress/expected/sanity_check.out b/src/test/regress/expected/sanity_check.out index 8d2b449f408..cebdc978dc2 100644 --- a/src/test/regress/expected/sanity_check.out +++ b/src/test/regress/expected/sanity_check.out @@ -189,6 +189,7 @@ timestamp_tbl|f timestamptz_tbl|f timetz_tbl|f varchar_tbl|f +view_base_table|t -- restore normal output mode \a\t -- diff --git a/src/test/regress/sql/create_view.sql b/src/test/regress/sql/create_view.sql index b4e7a8793cb..26bdbec0a42 100644 --- a/src/test/regress/sql/create_view.sql +++ b/src/test/regress/sql/create_view.sql @@ -24,6 +24,18 @@ COMMENT ON VIEW noview IS 'no view'; COMMENT ON VIEW toyemp IS 'is a view'; COMMENT ON VIEW toyemp IS NULL; +-- These views are left around mainly to exercise special cases in pg_dump. + +CREATE TABLE view_base_table (key int PRIMARY KEY, data varchar(20)); + +CREATE VIEW key_dependent_view AS + SELECT * FROM view_base_table GROUP BY key; + +ALTER TABLE view_base_table DROP CONSTRAINT view_base_table_pkey; -- fails + +CREATE VIEW key_dependent_view_no_cols AS + SELECT FROM view_base_table GROUP BY key HAVING length(data) > 0; + -- -- CREATE OR REPLACE VIEW --