| From: | Matthew Wakeling <matthew(at)flymine(dot)org> |
|---|---|
| To: | pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: Slow query with a lot of data |
| Date: | 2008-08-19 12:17:25 |
| Message-ID: | alpine.DEB.1.10.0808191311540.4454@aragorn.flymine.org |
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| Lists: | pgsql-performance |
On Tue, 19 Aug 2008, Moritz Onken wrote:
> tablename | attname | n_distinct | correlation
> result | domain | 1642 | 1
Well, the important thing is the correlation, which is 1, indicating that
Postgres knows that the table is clustered. So I have no idea why it is
sorting the entire table.
What happens when you run EXPLAIN SELECT * FROM result ORDER BY domain?
>> Sounds like an awfully long time to me. Also, I think restricting it to 280
>> users is probably not making it any faster.
>
> If I hadn't restricted it to 280 users it would have run ~350days...
What makes you say that? Perhaps you could post EXPLAINs of both of the
queries.
Matthew
--
What goes up must come down. Ask any system administrator.
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