From: Jim C. Nasby <jnasby@pervasive.com>
To: Simon Riggs <simon@2ndquadrant.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: WAL logging of SELECT ... INTO command
Date: Wed, 22 Mar 2006 07:19:10 -0600
Message-ID: <20060322131910.GC15742@pervasive.com> (raw)
In-Reply-To: <1143032914.24487.632.camel@localhost.localdomain>
References: <20060321122211.GU15742@pervasive.com>
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On Wed, Mar 22, 2006 at 01:08:34PM +0000, Simon Riggs wrote:
> On Wed, 2006-03-22 at 06:47 -0600, Jim C. Nasby wrote:
>
> > Also, why do we log rows for CTAS/SELECT INTO when PITR is in use for
> > simple SELECTs (ones that don't call non-deterministic functions)? The
> > data should alread be available AFAICS...
>
> Not sure what you're asking... SELECTs don't produce WAL.
Yes, there'd have to be some special kind of WAL entry that specifies
what select statement was used in CTAS.
> PITR wants all changes. Without PITR we can optimise certain logging
> actions.
The only change here is that we're creating a new table based on the
results of a SELECT. If that SELECT doesn't use anything that's
non-deterministic, then the machine doing the recovery should already
have all the data it needs, provided that we log the SELECT that was
used in the CTAS.
--
Jim C. Nasby, Sr. Engineering Consultant jnasby@pervasive.com
Pervasive Software http://pervasive.com work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461
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To: pgsql-performance@postgresql.org
Cc: jnasby@pervasive.com, simon@2ndquadrant.com
Subject: Re: WAL logging of SELECT ... INTO command
In-Reply-To: <20060322131910.GC15742@pervasive.com>
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