Thread: Drop or disable or bypass "_return" rule on select on a view.

Il 28.05.2015 08:23, Shashwat Arghode ha scritto:
> Hi all,
> I am using postgres 9.3.4 and have an on_select rule "_return" on a view.
> I want to drop or disable or bypass that rule.
> Is there any way it can be done without dropping the view??
>
> Because when i try to drop it, it returns
>
> ERROR:  cannot drop rule _RETURN on view viewname because view
> viewname requires it
> HINT:  You can drop viewname instead.
> CONTEXT:  SQL statement "drop rule "_RETURN" on viewname"
> PL/pgSQL function inline_code_block line 12 at EXECUTE statement
>
> and i don't want to drop the view.
>
> when i try to disable it using :
> alter table viewname disable rule _return
> it returns
> ERROR:  "viewname" is not a table
>
>
> Bypassing rule for a single query or disabling it for some time and
> then enable it will also work for me.
>
> Can it be done ?
>
> Thanks,
> Shashwat.

Hi Shashwat

I am no PG guru but I guess that, since "viewname" is a view and not a
table, you should use "alter view" and not "alter table". See:
http://www.postgresql.org/docs/9.3/static/sql-alterview.html

On Thu, May 28, 2015 at 8:23 AM, Shashwat Arghode
<shashwatarghode@gmail.com> wrote:
> Hi all,
> I am using postgres 9.3.4 and have an on_select rule "_return" on a view.
> I want to drop or disable or bypass that rule.
> Is there any way it can be done without dropping the view??
>
> Because when i try to drop it, it returns
>
> ERROR:  cannot drop rule _RETURN on view viewname because view viewname
> requires it
> HINT:  You can drop viewname instead.
> CONTEXT:  SQL statement "drop rule "_RETURN" on viewname"
> PL/pgSQL function inline_code_block line 12 at EXECUTE statement


I suspect you have messed up names, creating the rule on the target
table instead of another one used as a placeholder.
See the example here:
http://www.postgresql.org/docs/current/static/rules-views.html

Luca

Shashwat Arghode <shashwatarghode@gmail.com> writes:
> I am using postgres 9.3.4 and have an on_select rule "_return" on a view.
> I want to drop or disable or bypass that rule.
> Is there any way it can be done without dropping the view??

No.  I don't exactly see the point, either --- what do you imagine a view
without an ON SELECT rule would be good for?

Perhaps what you want is to replace the view with CREATE OR REPLACE VIEW,
which is basically equivalent to updating its ON SELECT rule.  But simply
dropping the rule without immediately replacing it would leave the view
nonfunctional.

            regards, tom lane

On Thu, May 28, 2015 at 8:53 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Shashwat Arghode <shashwatarghode@gmail.com> writes:
>> I am using postgres 9.3.4 and have an on_select rule "_return" on a view.
>> I want to drop or disable or bypass that rule.
>> Is there any way it can be done without dropping the view??
>
> No.  I don't exactly see the point, either --- what do you imagine a view
> without an ON SELECT rule would be good for?
>
> Perhaps what you want is to replace the view with CREATE OR REPLACE VIEW,
> which is basically equivalent to updating its ON SELECT rule.  But simply
> dropping the rule without immediately replacing it would leave the view
> nonfunctional.

Yeah.  If disabling the view is truly what's desired, and disabling a
view is defined as returning no data, you'd want to change:

CREATE OR REPLACE VIEW v AS SELECT ....

with

CREATE OR REPLACE VIEW v AS SELECT .... LIMIT 0;

Another option of course would be to drop it, but that would require
dealing with dependencies.   Still another option would be to have any
query against the view return an immediate exception:

CREATE OR REPLACE VIEW v AS SELECT .... WHERE (SELECT false FROM Error('test'));

Error() being a thin wrapper to plpgsql 'raise exception'.

merlin