Tuesday, August 19, 2008

Re: [PERFORM] Slow query with a lot of data

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

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