Re: optimizing Postgres queries

David Teran <david.teran@cluster9.com> writes:
> What we found out now is that a query with a single 'where' works fine,
> the query planer uses the index but when we have 'two' where clauses it
> does not use the index anymore:

> EXPLAIN ANALYZE SELECT columns...  FROM "KEY_VALUE_META_DATA" t0 WHERE
> (t0."ID_VALUE" = 14542); performs fine, less than one millisecond.

> EXPLAIN ANALYZE SELECT columns...  FROM "KEY_VALUE_META_DATA" t0 WHERE
> (t0."ID_VALUE" = 14542 OR t0."ID_VALUE" = 14550); performs bad: about
> 235 milliseconds.

Please, when you ask this sort of question, show the EXPLAIN ANALYZE
output.  It is not a virtue to provide minimal information and see if
anyone can guess what's happening.

            regards, tom lane