Content-Type: text/plain; charset="utf-8"
Date: Sat, 11 Sep 2010 19:08:37 +0200
From: "Steve" <steeeeeveee@gmx.net>
In-Reply-To: <npy1t0jod4jwhactu89sfrj7.1284213918770@email.android.com>
Message-ID: <20100911170837.240190@gmx.net>
MIME-Version: 1.0
References: <npy1t0jod4jwhactu89sfrj7.1284213918770@email.android.com>
Subject: Re: Question regarding indices
To: pgsql-sql@postgresql.org
Content-Transfer-Encoding: 8bit


-------- Original-Nachricht --------
> Datum: Sat, 11 Sep 2010 10:05:18 -0400
> Von: Michael Gould <mgould@intermodalsoftwaresolutions.net>
> An: Steve <steeeeeveee@gmx.net>
> Betreff: Re: [SQL] Question regarding indices

> Steve,
> 
Hello Michael,


> If I remember correctly the sort only works on the final result set and so
> doing a sort before the select isn't going to help
> 
I think you got me wrong. It's not that I want the RESULT to be sorted. I only asked if sorting the values in the query would have an effect on the speed of the query.

Or to ask it the other way around: Is an index in PostgreSQL sorted or not? If it is sorted and the PostgreSQL parser is looking for entries in the index then having the values pre-sorted would probably be beneficial. Right?


// Steve

> Sent from Samsung mobile
> 
> Steve <steeeeeveee@gmx.net> wrote:
> 
> >Hello List,
> >
> >I have a small question about the order of values in a query. Assume I
> have a table with the following fields:
> >  uid INT,
> >  data BIGINT,
> >  hits INT
> >
> >And an unique index on (uid, data). I use libpq C API to query data from
> the table. The query is something like this:
> >SELECT uid,data,hits FROM mytable WHERE uid=2 AND data IN
> (2033,2499,590,19,201,659)
> >
> >Would the speed of the query be influenced if I would sort the data? I
> can imagine that just querying a bunch of bigint would not make a big
> difference but what about several thousand of values? Would sorting them and
> sending the SQL query with ordered data influence the speed of the query?
> >
> >
> >// Steve
> >-- 
> >GRATIS: Spider-Man 1-3 sowie 300 weitere Videos!
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> >
> >-- 
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> >http://www.postgresql.org/mailpref/pgsql-sql

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