Re: left outer join terrible slow compared to inner join

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От Sean Chittenden
Тема Re: left outer join terrible slow compared to inner join
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Msg-id 20030828183139.GL83759@perrin.nxad.com
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Ответ на Re: left outer join terrible slow compared to inner join  ("Clay Luther" <claycle@cisco.com>)
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> Actually, I was about to post some problems we have with large left
> outer joins as well we've discovered in a porting project from
> NT/SQL Server -> Linux/Postgres.
>
> We have a particular query that is rather large, left outer joining
> across several tables.  Under SQL Server, with identical data and
> schema, this particular query takes 2 seconds.
>
> Under PostgreSQL, this same query takes 90 seconds -- that's right,
> 90 seconds.  45x longer than SQL Server.  This was quite a shock to
> us (we'd not seen such a performance deficit between the two dbs
> until this) and could, in fact, force us away from Postgres.
>
> I'd be happy to forward the explain to anyone who'd care to look at
> it...

Post an EXPLAIN ANALYZE of the query...

-sc

--
Sean Chittenden

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