Re: Slow query to get last created row using CURRVAL - Mailing list pgsql-performance

On Sat, Dec 4, 2010 at 13:56, Mathieu De Zutter <mathieu@dezutter.org> wrote:
> I have no idea why in some cases the index scan is not considered.
> Does anyone have an idea?

I guess that it's because the currval() function is volatile -- its
value has to be tested for again each row.

Try this instead:
SELECT user_id FROM log_event WHERE id = (SELECT CURRVAL('log_event_id_seq'));

This will assure that there's only one call to currval().

Regards,
Marti