On Saturday, January 12, 2013 7:17 AM T. E. Lawrence wrote: > Hello, > I have a pretty standard query with two tables: > SELECT table_a.id FROM table_a a, table_b b WHERE ... AND ... AND b.value=...; > With the last "AND b.value=..." the query is extremely slow (did not wait for it to end, but more than a minute), because the value column is not indexed (contains items longer than 8K). > However the previous conditions "WHERE ... AND ... AND" should have already reduced the candidate rows to just a few (table_b contains over 50m rows). And indeed, removing the last "AND b.value=..." speeds the query to just a millisecond. > Is there a way to instruct PostgreSQL to do first the initial "WHERE ... AND ... AND" and then the last "AND b.value=..." on the (very small) result? You can try once with below query: Select * from (SELECT a.id,b.value FROM table_a a, table_b b WHERE ... AND ... ) X where X.value=...; If this doesn't work can you send the Explain .. output for both queries(the query you are using and the query I have suggested) With Regards, Amit Kapila. -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
