> I just want to retrieve that id 's from page_content which do not have > any entry in clause2 table.
In that case the query probably does not work (at least the query you've sent in the first post) as it will return even those IDs that have at least one other row in 'clause2' (not matching the != condition). At least that's how I understand it. So instead of this select distinct(p.crawled_page_id) from page_content p, clause2 c where p.crawled_page_id != c.source_id ; you should probably do this select distinct(p.crawled_page_id) from page_content p left join clause2 c on (p.crawled_page_id = c.source_id) where (c.source_id is null); I guess this will be much more efficient too. regards Tomas -- Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
