Re: Get Postgres to use multiple proc cores?

"Oliveiros d'Azevedo Cristina" 
wrote:
 
> What is faster? A JOIN or a WHERE a IN (SELECT ... )
 
On 8.4 and later an EXISTS or NOT EXISTS will use semi-join or
anti-join (respectively).  These should usually be much faster than
the IN (SELECT DISTINCT ... ) technique.  Be careful of the
difference in semantics between NOT EXISTS and NOT IN if any of the
columns involved in the matching can be null -- they are *not* the
same thing.
 
-Kevin