Re: Indexes not working (bug in 7.0.2?)

Zlatko Calusic <zlatko@iskon.hr> writes:
> It is now NOT using the index, and I don't understand why? Queries are
> practically the same, tables are practically the same, why is postgres
> using indexes in the first case and not in the second?

Because it has substantially different ideas about the sizes of the
two tables --- notice the different estimated row counts.  If you
haven't "vacuum analyzed" these tables recently, do so to bring the
planner's statistics up-to-date, and then see what you get.  You may
also care to read the user's manual chapter about EXPLAIN,
http://www.postgresql.org/users-lounge/docs/7.0/postgres/c4888.htm

            regards, tom lane