Re: ON SELECT rule on a table without columns

[Ashutosh Sharma]

On Fri, Feb 8, 2019 at 7:55 PM Tom Lane <t...@sss.pgh.pa.us> wrote:
>
> Andres Freund <and...@anarazel.de> writes:
> > You misunderstood my point: I'm asking why we shouldn't remove that check 
> > from views, rather than adding it to create rule.
>
> +1.  This seems pretty obviously to be something we just missed when
> we changed things to allow zero-column tables.
>

Thanks Andres for bringing up that point and thanks Tom for the confirmation.

Attached is the patch that allows us to create view on a table without
columns. I've also added some test-cases for it in create_view.sql.
Please have a look and let me know your opinion.

-- 
With Regards,
Ashutosh Sharma
EnterpriseDB:http://www.enterprisedb.com

diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 65f4b40..c49ae97 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -111,10 +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
diff --git a/src/test/regress/expected/create_view.out b/src/test/regress/expected/create_view.out
index 141fc6d..ee41c40 100644
--- a/src/test/regress/expected/create_view.out
+++ b/src/test/regress/expected/create_view.out
@@ -1706,9 +1706,16 @@ select pg_get_ruledef(oid, true) from pg_rewrite
      43 AS col_b;
 (1 row)
 
+-- create view on a table without columns
+create table t0();
+create view v0 as select * from t0;
+select * from v0;
+--
+(0 rows)
+
 -- clean up all the random objects we made above
 \set VERBOSITY terse \\ -- suppress cascade details
 DROP SCHEMA temp_view_test CASCADE;
 NOTICE:  drop cascades to 27 other objects
 DROP SCHEMA testviewschm2 CASCADE;
-NOTICE:  drop cascades to 62 other objects
+NOTICE:  drop cascades to 64 other objects
diff --git a/src/test/regress/sql/create_view.sql b/src/test/regress/sql/create_view.sql
index 9480030..e5ca690 100644
--- a/src/test/regress/sql/create_view.sql
+++ b/src/test/regress/sql/create_view.sql
@@ -580,6 +580,11 @@ select pg_get_viewdef('tt23v', true);
 select pg_get_ruledef(oid, true) from pg_rewrite
   where ev_class = 'tt23v'::regclass and ev_type = '1';
 
+-- create view on a table without columns
+create table t0();
+create view v0 as select * from t0;
+select * from v0;
+
 -- clean up all the random objects we made above
 \set VERBOSITY terse \\ -- suppress cascade details
 DROP SCHEMA temp_view_test CASCADE;