Thomas Kappler <tkappler@xxxxxxxxxxxxxx> writes: > The query we want to do is (with example values): > select t.cid, count(distinct t1.subject_id) > from termindex t1, termindex t2 > where t1.cid=20642 and t1.indextype=636 and t2.indextype=636 and > t2.subject_id=t1.subject_id > group by t2.cid; The EXPLAIN output you provided doesn't appear to match this query (in particular, I don't see the indextype restrictions being checked anyplace in the plan). One quick-and-dirty thing that might help is to raise work_mem enough so that (1) you get a hash aggregation not a sort/group one, and (2) if there are still any sorts being done, they don't spill to disk. That will probably be a higher number than would be prudent to install as a global setting, but you could SET it locally in the current session before issuing the expensive query. regards, tom lane -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
