Prolem wiht long query?

Hi,

I have some trouble with a very long query.

This Query run well :
----------------

select *
from
adresses, liaison_adresse_rubrique as lar0,
liaison_adresse_rubrique as lar1,
liaison_adresse_rubrique as lar2
where
lar0.refadresse=adresses.ref
and lar0.refrubrique=73
and lar1.refadresse=adresses.ref
and lar1.refrubrique=151
and lar2.refadresse=adresses.ref
and lar2.refrubrique=170

This Query take a lot of time :
-----------------------

select *
from
adresses, liaison_adresse_rubrique as lar0,
liaison_adresse_rubrique as lar1,
liaison_adresse_rubrique as lar2,
liaison_adresse_rubrique as lar3,
liaison_adresse_rubrique as lar4
where
lar0.refadresse=adresses.ref
and lar0.refrubrique=73
and lar1.refadresse=adresses.ref
and lar1.refrubrique=150
and lar2.refadresse=adresses.ref
and lar2.refrubrique=160
and lar3.refadresse=adresses.ref
and lar3.refrubrique=151
and lar4.refadresse=adresses.ref
and lar4.refrubrique=170

This Query never finish, and take all my memory (and I have 384Mb)
---------------------------------------------------
select *
from
adresses, liaison_adresse_rubrique as lar0,
liaison_adresse_rubrique as lar1,
liaison_adresse_rubrique as lar2,
liaison_adresse_rubrique as lar3,
liaison_adresse_rubrique as lar4,
liaison_adresse_rubrique as lar5,
liaison_adresse_rubrique as lar6
where
lar0.refadresse=adresses.ref
and lar0.refrubrique=73
and lar1.refadresse=adresses.ref
and lar1.refrubrique=148
and lar2.refadresse=adresses.ref
and lar2.refrubrique=153
and lar3.refadresse=adresses.ref
and lar3.refrubrique=150
and lar4.refadresse=adresses.ref
and lar4.refrubrique=160
and lar5.refadresse=adresses.ref
and lar5.refrubrique=151
and lar6.refadresse=adresses.ref
and lar6.refrubrique=170

Every think is index using hash table.

Is it a limitation of pg?

Do you know another method to do that?

Is it exist an intersect operator in pg (like in oracle)?

Jérome knobl, Lausanne, Switzerland