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Re: COPY LOCK for WAL bypass

From: "Jim C(dot) Nasby" <jnasby(at)pervasive(dot)com>
To: Simon Riggs <simon(at)2ndquadrant(dot)com>
Cc: Chris Browne <cbbrowne(at)acm(dot)org>, pgsql-patches(at)postgresql(dot)org
Subject: Re: COPY LOCK for WAL bypass
Date: 2005-12-20 18:47:27
Message-ID: 20051220184727.GA28771@pervasive.com (view raw or flat)
Thread:
Lists: pgsql-patches
On Mon, Dec 19, 2005 at 07:51:54AM +0000, Simon Riggs wrote:
> On Sun, 2005-12-18 at 22:03 -0500, Chris Browne wrote:
> > simon(at)2ndquadrant(dot)com (Simon Riggs) writes:
> > > On Sat, 2005-12-10 at 12:07 +0000, Simon Riggs wrote:
> > >> Following patch implements COPY ... FROM ... LOCK
> > >
> > > Patch now updated so that it includes an additional optimization of
> > > COPY, so that WAL will not be written in the transaction that created
> > > the table.
> > >
> > > This now gives two fast paths for COPY:
> > > 1) COPY LOCK
> > > 2) COPY in same transaction (e.g. reloading a pg_dump)
> > 
> > I presume that if this doesn't go into WAL, that means that this kind
> > of update wouldn't play with PITR, right?
> 
> You're right.
> 
> PITR is designed for normal production use, rather than initial loading.
> It is also fairly common to turn PITR off permanently in larger data
> warehouses, which is also where these optimizations are aimed.

Hrm... I'd say we need an option to disable the fast-copy then, in case
you wanted the copy to make it into PITR. Or perhaps we just disallow
the fast-copy when PITR is in use. I believe that's what other databases
do...
-- 
Jim C. Nasby, Sr. Engineering Consultant      jnasby(at)pervasive(dot)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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