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Fix CREATE VIEW to allow zero-column views.

2019年2月17日 17:37:31 +0000 (12:37 -0500)

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 patch | blob | blame | history

src/test/regress/expected/create_view.out patch | blob | blame | history

src/test/regress/expected/rules.out patch | blob | blame | history

src/test/regress/expected/sanity_check.out patch | blob | blame | history

src/test/regress/sql/create_view.sql patch | blob | blame | history

diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c

index 65f4b40b38f6131a1295c01dbf8c5343a382ac64..87ed453649b92af5f5c76a7a9dbe5e688c608c44 100644 (file)

--- 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 141fc6da62a87ba9fd8183dd4a24a2f13158d054..340e5a1c1a4b5e975f39bf7e695326dcc189260a 100644 (file)

--- 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 95b8a95fa2eeb250d38efe311f940fa25a81a4f2..98f417cb57cfec019bc9a3648c70936f11404b97 100644 (file)

--- 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 89537bcfcf4a6cd914fbeced27bee3c9e4d97dbf..6cd937eb52bdfb57610982cc9df97b39be642e2a 100644 (file)

--- a/src/test/regress/expected/sanity_check.out

+++ b/src/test/regress/expected/sanity_check.out

@@ -205,6 +205,7 @@ 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 9480030005eeb5a889adcb67be6f155d07204f87..845505caa65b7863720dda991239fe8ccdc4133b 100644 (file)

--- 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';