"vinita bansal" <sagivini@hotmail.com> writes:
> Also, a particular query which was taking a min or less with postgres 7 is
> taking 15 mins now.
> Here is the query plan for the query both for postgres 7.4.6 and postgres 8:
It's hard to say anything about this when you only provided EXPLAIN and
not EXPLAIN ANALYZE results. The rowcount estimates are obviously a lot
different between 7.4 and 8.0, but are they more accurate or less so?
Can't tell from EXPLAIN.
> Why is this happening.
Have you vacuumed and/or analyzed all of the tables used in the query?
It looks like a statistical estimation problem to me. People frequently
complain that a new version has horrible performance because they forgot
to analyze their database after migrating ...
regards, tom lane