From: pginfo <pginfo@t1.unisoftbg.com>
To: Philip Warner <pjw@rhyme.com.au>
Cc: pgsql-sql@postgresql.org <pgsql-sql@postgresql.org>
Subject: Re: problem with max and not using index on PK
Date: Sat, 03 May 2003 14:36:48 +0200
Message-ID: <3EB3B7E0.5E6030AE@t1.unisoftbg.com> (raw)
References: <5.1.0.14.0.20030503220308.02bcfe68@mail.rhyme.com.au>
It is working in this case.
I see that using "order by" make the query slower by 25% if I start it on
another column.
Alse as I wrote in oracle the max use indexes.
regards,
ivan.
Philip Warner wrote:
> At 11:12 AM 3/05/2003 +0200, pginfo wrote:
> >I do not know the reason for not using index in this case.
>
> PostgreSQL does not know that it can use the index, and the query example
> you gave is about the only case in which it can use the index. You can get
> it to use an index by rewriting it as:
>
> select IDS from t_sk10 order by IDS desc limit 1;
>
> ...nowhere near as nice, but it works.
>
> ----------------------------------------------------------------
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To: pgsql-sql@postgresql.org
Cc: pginfo@t1.unisoftbg.com, pjw@rhyme.com.au
Subject: Re: problem with max and not using index on PK
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