From: Markus Schaber <schabi@logix-tt.com>
To: PostgreSQL Performance List <pgsql-performance@postgresql.org>
Subject: Re: Index on two columns not used
Date: Mon, 23 Oct 2006 17:17:06 +0200
Message-ID: <453CDCF2.6090208@logix-tt.com> (raw)
In-Reply-To: <20061023135011.GG7961@alvh.no-ip.org>
References: <45360E25.9010403@freesurf.fr>
<45361295.9050504@enterprisedb.com>
<4539F4E1.7000003@chemaxon.hu>
<453CC2DD.4070608@logix-tt.com>
<20061023135011.GG7961@alvh.no-ip.org>
Hi, Alvaro,
Alvaro Herrera wrote:
>> Additionally, in most UPDATE cases, the new row version will fit into
>> the same page as the old version. In this case, the index does not have
>> to be changed, which is an additional speed improvement.
> Actually, when the UPDATE puts a new row version in the same heap page,
> the index must be updated anyway.
AFAICS only, when the index covers (directly or via function) a column
that's actually changed.
Changing columns the index does not depend on should not need any write
access to that index.
Correct me if I'm wrong.
Thanks,
Markus
--
Markus Schaber | Logical Tracking&Tracing International AG
Dipl. Inf. | Software Development GIS
Fight against software patents in Europe! www.ffii.org
www.nosoftwarepatents.org
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To: pgsql-performance@postgresql.org
Cc: schabi@logix-tt.com
Subject: Re: Index on two columns not used
In-Reply-To: <453CDCF2.6090208@logix-tt.com>
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