On Wed, Oct 19, 2011 at 7:36 AM, Robert Haas <robertmh...@gmail.com> wrote: > On Tue, Sep 6, 2011 at 1:43 PM, Bruce Momjian <br...@momjian.us> wrote: >> Well, this problem isn't isolated to WITH queries: >> >> test=> do >> $$begin >> perform( >> select 1 UNION ALL select 1 >> ); >> end$$; >> ERROR: more than one row returned by a subquery used as an expression >> >> test=> do >> $$begin >> perform( >> select relname from pg_class >> ); >> end$$; >> ERROR: more than one row returned by a subquery used as an expression >> > > Based on previous experience with PL/pgsql, my understanding is that > PL/pgsql basically replaces "perform" with "select" to get the query > that it actually runs. You'd get the same error from: > > rhaas=# select (select relname from pg_class); > ERROR: more than one row returned by a subquery used as an expression > > I've never really liked this behavior, but I don't have a clear idea > what to do about it.
yeah. it's an interesting thought experiment to try and come up with a wrapper in the form of wrap(query); That's efficient, guarantees that 'query' is completely run, and does not error no matter how many rows or columns 'query' comes back with. I've got: select min(1) from (query) q; The point being, how do I convert any query to a non WITH variant so it can be PERFORM'd? Anyways, I always thought having to do perform at all was pretty weak sauce -- not sure why it's required. merlin -- Sent via pgsql-bugs mailing list (pgsql-bugs@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-bugs
