On Sat, Dec 4, 2010 at 13:56, Mathieu De Zutter <mathieu(at)dezutter(dot)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