Skip site navigation (1) Skip section navigation (2)

Re: Various performance questions

From: Neil Conway <neilc(at)samurai(dot)com>
To: Tarhon-Onu Victor <mituc(at)iasi(dot)rdsnet(dot)ro>
Cc: Dror Matalon <dror(at)zapatec(dot)com>,PostgreSQL Performance <pgsql-performance(at)postgresql(dot)org>
Subject: Re: Various performance questions
Date: 2003-10-27 15:34:53
Message-ID: 1067268893.460.31.camel@tokyo (view raw, whole thread or download thread mbox)
Lists: pgsql-performance
On Mon, 2003-10-27 at 10:15, Tarhon-Onu Victor wrote:
> select count(*) from items where channel < 
> 5000; will never use any of the current indexes because none matches 
> your WHERE clause (channel appears now only in multicolumn indexes).

No -- a multi-column index can be used to answer queries on a prefix of
the index's column list. So an index on (channel, xyz) can be used to
answer queries on (just) "channel".


In response to

pgsql-performance by date

Next:From: Neil ConwayDate: 2003-10-27 15:41:49
Subject: Re: Various performance questions
Previous:From: Christopher Kings-LynneDate: 2003-10-27 15:16:05
Subject: Linux Filesystem Shootout

Privacy Policy | About PostgreSQL
Copyright © 1996-2017 The PostgreSQL Global Development Group