Re: [HACKERS] disallow LOCK on a view - the Tom Lane remix

Alfred Perlstein <bright@wintelcom.net> writes:
> Ok, I'm wondering if this patch will cause problems locking a table
> that has had:
> CREATE RULE "_RETfoo" AS ON SELECT TO foo DO INSTEAD SELECT * FROM foo1;
> I need to be able to lock the table 'foo' exclusively while I swap
> out the underlying rule to forward to another table.

Uh, do you actually need any sort of lock for that?

Seems to me that if you do
    BEGIN;
    DELETE RULE "_RETfoo";
    CREATE RULE "_RETfoo" AS ...;
    COMMIT;
then any other transaction will see either the old rule definition
or the new one.  No intermediate state, no need for a lock as such.

BTW, this seems to be a counterexample for my prior suggestion that
pg_class should have a "relviewrule" OID column.  If it did, you'd
have to update that field when doing something like the above.
Pain-in-the-neck factor looms large...

            regards, tom lane