Re: COPY with no WAL, in certain circumstances

From: Bruce Momjian <bruce(at)momjian(dot)us>
To: "Joshua D(dot) Drake" <jd(at)commandprompt(dot)com>
Cc: Simon Riggs <simon(at)2ndquadrant(dot)com>, pgsql-patches(at)postgresql(dot)org
Subject: Re: COPY with no WAL, in certain circumstances
Date: 2007-01-06 17:31:51
Message-ID: 200701061731.l06HVpg22109@momjian.us
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Joshua D. Drake wrote:
> On Sat, 2007-01-06 at 11:05 -0500, Bruce Momjian wrote:
> > FYI, I am going need to add documentation in the COPY manual page or no
> > one will know about this performance enhancement.
>
> I have some questions:
>
> > > As discussed on -hackers, its possible to avoid writing any WAL at all
> > > for COPY in these circumstances:
> > >
> > > BEGIN;
> > > CREATE TABLE foo..
> > > COPY foo...
> > > COMMIT;
>
> What if I do this?
>
> BEGIN;
> CREATE TABLE foo...
> INSERT INTO foo VALUES ('1');
> COPY foo...
>
> COMMIT;

On ABORT, the entire table disappears, as well as the INSERT, so I don't
see any problem. I assume the INSERT is WAL logged.

--
Bruce Momjian bruce(at)momjian(dot)us
EnterpriseDB http://www.enterprisedb.com

+ If your life is a hard drive, Christ can be your backup. +

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