Re: postgres 9 query performance - Mailing list pgsql-performance

On Sunday 30 January 2011 23:18:15 Tom Lane wrote:
> Andres Freund <andres@anarazel.de> writes:
> > What happens if you change the
> >
> >     left join event.origin on event.id = origin.eventid
> >
> > into
> >
> >     join event.origin on event.id = origin.eventid
> >
> > ?
> >
> > The EXISTS() requires that origin is not null anyway. (Not sure why the
> > planner doesn't recognize that though).
>
> Sloppy thinking in reduce_outer_joins() is why.
Wow. Nice one, thanks.

Andres