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Re: database performance and query performance question

From: Hannu Krosing <hannu(at)tm(dot)ee>
To: "Shea,Dan [CIS]" <Dan(dot)Shea(at)ec(dot)gc(dot)ca>
Cc: "'josh(at)agliodbs(dot)com'" <josh(at)agliodbs(dot)com>,pgsql-performance(at)postgresql(dot)org
Subject: Re: database performance and query performance question
Date: 2004-01-22 20:53:37
Message-ID: 1074804816.2592.4.camel@fuji.krosing.net (view raw or flat)
Thread:
Lists: pgsql-performance
Hannu Krosing kirjutas N, 22.01.2004 kell 22:46:
> Shea,Dan [CIS] kirjutas N, 22.01.2004 kell 22:35:
> > Something that I do not understand is why if you use a valid_time =
> > '2004-01-22 00:00:00' the query will use the index but if you do a
> > valid_time >  '2004-01-22 00:00:00' it does not use the index?
> 
> It probably can't tell if > is selective enough to justify using index.
> 
> Together with "limit 10" it may be.
> 
> You could try 
> 
> explain analyze select * from forecastelement where valid_time between 
> '2004-01-22'::date and '2004-01-22'::date limit 10;

Sorry, that should have been:

between '2004-01-22'::date and '2004-01-23'::date


> to see if this is considered good enough.
> 
> --------------
> Hannu
> 
> 
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