Re: performance on query

So the issue is that instead of taking 174 seconds the query now takes
201?

I'm guessing that SQL server might be using index covering, but that's
just a guess. Posting query plans (prefferably with actual timing info;
EXPLAIN ANALYZE on PostgreSQL and whatever the equivalent would be for
MSSQL) might give us some idea.

On Wed, Oct 26, 2005 at 05:47:31PM -0600, Sidar L?pez Cruz wrote:
> I DON'T KNOW WHAT TO DO WITH THIS QUERYS...
> Comparation with sql server, sql server wins !!!
>
>
> Table sizes:
> archivos: 40MB
> fotos: 55MB
>
> select count(1) from fotos f where not exists (select a.archivo from
> archivos a where a.archivo=f.archivo)
> 173713 ms.
> 110217 ms.
> 83122 ms.
>
> select count(*) from
> (
> select archivo from fotos
> except
> select archivo from archivos
> ) x;
> 201479 ms.
>
> SELECT count(*)
> FROM fotos f
> LEFT JOIN archivos a USING(archivo)
> WHERE a.archivo IS NULL
> 199523 ms.
>
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Jim C. Nasby, Sr. Engineering Consultant jnasby(at)pervasive(dot)com
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