Re: need much better query perfomance - Mailing list pgsql-general

On 24 Jan 2003, Andy wrote:

> I wrote what must be a very naive query to find such tracks.  Doing an
> explain on this query gave a huge time estimate.  My query is below.
> Would someone please suggest a faster approach?
>
>   select t.track_id
>     from track t
>     where t.deleted = 'Y'
>       UNION
>   select track_id from track where track_id not in (
>     select at.track_id from album_track at, album alb
>       where at.album_id = alb.album_id and alb.deleted is null
>   )

Try converting the in query into EXISTS
something like
select track_id from track where not exists (
 select at.track_id from album_track at, album alb where
  at.album_id=alb.album_id and alb.deleted is null and
  track.track_id=at.track_id;
 );