From: Kevin Grittner <kgrittn@mail.com>
To: Benjamin Krajmalnik <kraj@servoyant.com>
To: pgsql-admin@postgresql.org
Subject: Re: Schema design question as it pertains to performance
Date: Tue, 22 Jan 2013 19:23:01 -0500
Message-ID: <20130123002301.120590@gmx.com> (raw)
List-Unsubscribe: <mailto:majordomo@postgresql.org?body=unsub%20pgsql-admin>
Benjamin Krajmalnik wrote:
> Kevin Grittner wrote:
>> Benjamin Krajmalnik wrote:
>>> I also assume that if no data has changed in an index, nothing
>>> is done when the record is updated as pertains to the
>>> particular index - am I correct in this assumption?
>>
>> No. [...] If any indexed column is updated, [...] it needs new
>> entries in all the indexes.
> That was my intent - if no column of an index changes in an
> update then no changes are done on the index.
I don't think you understood -- if any column referenced by any
index is updated, then all indexes must get a new entry for that
row whether or not they include that column. The new version of the
row will be at a new location, so new entries are needed in all
indexes to point to the new location.
I did *not* say that only indexes referencing the updated column
need a new entry.
-Kevin
--
Sent via pgsql-admin mailing list (pgsql-admin@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-admin
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-admin@postgresql.org
Cc: kgrittn@mail.com, kraj@servoyant.com
Subject: Re: Schema design question as it pertains to performance
In-Reply-To: <20130123002301.120590@gmx.com>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox