Re: Optimizer Bug?

On Tue, 30 May 2000, Mitterwald, Holger wrote:

> If I execute the following statement:
> query: explain select k.name, t.lang from kneipe k, typ t where
> k.typ=t.typ;
> ProcessUtility: explain select k.name, t.lang from kneipe k, typ t where
> k.typ=t.typ;

> Seems ok to me, but if I insert a (huge) table which is nowhere
> referenced (here:"preis"), the
> following happens:
>
> query: explain select k.name, t.lang from kneipe k, typ t, preis p where
> k.typ=t.typ;

> The query takes up to 100 times longer although the table "preis" is not
> used at all.

Sure it's used. Just because it's not mentioned in the select list doesn't
mean it will be ignored completely. What you get here is a three-way join,
which is of course slower than a two way join.

--
Peter Eisentraut Sernanders väg 10:115
peter_e(at)gmx(dot)net 75262 Uppsala
http://yi.org/peter-e/ Sweden