Re: hash semi join caused by "IN (select ...)"

Clemens Eisserer <linuxhippy@gmail.com> writes:
> I have a quite complex, performance sensitive query in a system with a
> few (7) joins:
> select .... from t1 left join t2 .... WHERE id IN (select ....)

Does it work as expected with one less join?  If so, try increasing
join_collapse_limit ...

            regards, tom lane