From: Andrew Sullivan <ajs@crankycanuck.ca>
To: pgsql-sql@postgresql.org
Subject: Re: Versionning (was: Whole-row comparison)
Date: Fri, 1 Jun 2007 14:51:25 -0400
Message-ID: <20070601185125.GJ24299@phlogiston.dyndns.org> (raw)
In-Reply-To: <CCC9DCA122011F4CA593F6A548BFFBD362FCFE@esebe111.NOE.Nokia.com>
References: <CCC9DCA122011F4CA593F6A548BFFBD354D259@esebe111.NOE.Nokia.com>
<473557.7523.qm@web31803.mail.mud.yahoo.com>
<CCC9DCA122011F4CA593F6A548BFFBD354D260@esebe111.NOE.Nokia.com>
<CCC9DCA122011F4CA593F6A548BFFBD362FCF9@esebe111.NOE.Nokia.com>
<20070601174711.GH24299@phlogiston.dyndns.org>
<CCC9DCA122011F4CA593F6A548BFFBD362FCFE@esebe111.NOE.Nokia.com>
On Fri, Jun 01, 2007 at 09:07:10PM +0300, christian.roche.ext@nsn.com wrote:
>
> Hi Andrew,
>
> I must admit I don't really understand what you say. I don't know what
> SRF stand for, and what you say about generic case is not clear to me,
> sorry.
Sorry, it stands for set returning function. I thought someone
upthread suggested that instead of a view.
> and the following statement would be optimized:
>
> UPDATE param_table SET ver_id = xxx;
> SELECT * FROM bsc_view WHERE obj_id = yyy;
>
> which would not be the case would I have used a multi-row function.
>
> Does this make sense ?
Yes, but I don't think it's true. Because you change the value of
ver_id all the time, the actual result can't be collapsed to a
constant, so you end up having to execute the query with the
additional value, and you still have to plan that. The same thing is
true of a function, which will have its plan prepared the first time
you execute it. (I could be wrong about this; I suppose the only way
would be to try it.)
A
--
Andrew Sullivan | ajs@crankycanuck.ca
However important originality may be in some fields, restraint and
adherence to procedure emerge as the more significant virtues in a
great many others. --Alain de Botton
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-sql@postgresql.org
Cc: ajs@crankycanuck.ca
Subject: Re: Versionning (was: Whole-row comparison)
In-Reply-To: <20070601185125.GJ24299@phlogiston.dyndns.org>
* 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