| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | "vinita bansal" <sagivini(at)hotmail(dot)com> |
| Cc: | mrylander(at)gmail(dot)com, pgsql-general(at)postgresql(dot)org |
| Subject: | Re: postgres 8 settings |
| Date: | 2005-03-12 16:57:16 |
| Message-ID: | 25668.1110646636@sss.pgh.pa.us |
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| Thread: | |
| Lists: | pgsql-general |
"vinita bansal" <sagivini(at)hotmail(dot)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
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