Hi All,
When "ON SELECT" rule is created on a table without columns, it
successfully converts a table into the view. However, when the same is
done using CREATE VIEW command, it fails with an error saying: "view
must have at least one column". Here is what I'm trying to say:
-- create table t1 without columns
create table t1();
-- create table t2 without columns
create table t2();
-- create ON SELECT rule on t1 - this would convert t1 from table to view
create rule "_RETURN" as on select to t1 do instead select * from t2;
-- now check the definition of t1
\d t1
postgres=# \d+ t1
View "public.t1"
Column | Type | Collation | Nullable | Default | Storage | Description
--------+------+-----------+----------+---------+---------+-------------
View definition:
SELECT
FROM t2;
The output of "\d+ t1" shows the definition of converted view t1 which
doesn't have any columns in the select query.
Now, when i try creating another view with the same definition using
CREATE VIEW command, it fails with the error -> ERROR: view must have
at least one column. See below
postgres=# create view v1 as select from t2;
ERROR: view must have at least one column
OR,
postgres=# create view v1 as select * from t2;
ERROR: view must have at least one column
Isn't that a bug in create rule command or am i missing something here ?
If it is a bug, then, attached is the patch that fixes it.
--
With Regards,
Ashutosh Sharma
EnterpriseDB:http://www.enterprisedb.com
diff --git a/src/backend/rewrite/rewriteDefine.c b/src/backend/rewrite/rewriteDefine.c
index 3496e6f..cb51955 100644
--- a/src/backend/rewrite/rewriteDefine.c
+++ b/src/backend/rewrite/rewriteDefine.c
@@ -473,6 +473,11 @@ DefineQueryRewrite(const char *rulename,
errmsg("could not convert table \"%s\" to a view because it has row security enabled",
RelationGetRelationName(event_relation))));
+ if (event_relation->rd_rel->relnatts == 0)
+ ereport(ERROR,
+ (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+ errmsg("view must have at least one column")));
+
if (relation_has_policies(event_relation))
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
