Re: Index scan startup time

Am Donnerstag, 30. März 2006 14:02 schrieb Steinar H. Gunderson:
> On Thu, Mar 30, 2006 at 01:59:10PM +0200, Peter Eisentraut wrote:
> > EXPLAIN ANALYZE select activity_id from activity where state in (10000,
> > 10001) order by activity_id limit 100;
> >
> > QUERY PLAN
> >
> > Limit (cost=0.00..622.72 rows=100 width=8) (actual
> > time=207356.054..207356.876 rows=100 loops=1)
> > -> Index Scan using activity_pk on activity (cost=0.00..40717259.91
> > rows=6538650 width=8) (actual time=207356.050..207356.722 rows=100
> > loops=1) Filter: ((state = 10000) OR (state = 10001))
> > Total runtime: 207357.000 ms
> >
> > The table has seen VACUUM FULL and REINDEX before this.
>
> The index scan is by activity_id, not by state. Do you have an index on
> state at all?

There is an index on state as well but the column is not selective enough.

--
Peter Eisentraut
http://developer.postgresql.org/~petere/