amount of join's and sequential access to the tables involved

Hi all. Im working on a 'simple' query with 7, 8 left joins. After the
9nth join or so, explain analyze became to show the plan with many
tables being read in sequential fashion. Of course, this slows down the
query response in a factor on 10.

I can alter the order in wich the join's are appended, allways with the
same result.

So,it looks like a resources config situation.

Wich config variables are involved in the use of hash joins?

(I dont have access right now to the server running pg, so i cannot show
query plan nor pg configuration)

Thanks!

Gerardo