Re: simpler query significantly slower

> twanger@smartvia.de writes:
> >     select
> >         distinct
> >         gruppen_produkte.produktgruppen_id
> >     from
> >         r_gruppen_produkte
> >     where
> >         r_gruppen_produkte.gruppen_id = gruppen.
> gruppen_id             // this and the next cond are
> removed in 2nd query
> >     and
> >         gruppen.parent_id=1
> >     and
> >         r_gruppen_produkte.gruppen_id =
> r_personen_bereiche.g_id
> >     and
> >         r_personen_bereiche.p_id = 1234
> This SQL seems rather seriously confused.  It
> looks to me like you will
> get back one copy of each distinct
> produktgruppen_id value appearing in
> gruppen_produkte.  Since no gruppen_produkte
> field is constrained by
> WHERE, none will be eliminated.  All that the
> rest of the query does is
> cause a completely useless Cartesian-product
> join against some subset
> of r_gruppen_produkte * gruppen *
> r_personen_bereiche.
> Possibly you meant to select from
> r_gruppen_produkte.
> BTW, PG 7.1 would have complained about the
> lack of FROM entries for
> gruppen_produkte, gruppen, and
> r_personen_bereiche, which might have
> clued you to your error ...
>             regards, tom lane

Yeah sorry, you are right, but the typo is only in my posting. The query does actually query r_gruppen_produkte.