Re: WAL format changes

From: Alvaro Herrera <alvherre(at)commandprompt(dot)com>
To: Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>
Cc: Robert Haas <robertmhaas(at)gmail(dot)com>, Fujii Masao <masao(dot)fujii(at)gmail(dot)com>, Andres Freund <andres(at)2ndquadrant(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: WAL format changes
Date: 2012-06-26 00:42:43
Message-ID: 1340671279-sup-3382@alvh.no-ip.org
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Excerpts from Heikki Linnakangas's message of lun jun 25 20:09:34 -0400 2012:
> On 25.06.2012 21:01, Robert Haas wrote:
> > On Mon, Jun 25, 2012 at 1:57 PM, Fujii Masao<masao(dot)fujii(at)gmail(dot)com> wrote:
> >>> "<<" should be">>". The attached patch fixes this typo.
> >>
> >> Oh, I forgot to attach the patch.. Here is the patch.
> >
> > I committed both of the patches you posted to this thread.
>
> Thanks Robert. I was thinking that "pg_resetxlog -l" would accept a WAL
> file name, instead of comma-separated tli, xlogid, segno arguments. The
> latter is a bit meaningless now that we don't use the xlogid+segno
> combination anywhere else. Alvaro pointed out that pg_upgrade was broken
> by the change in pg_resetxlog -n output - I changed that too to print
> the "First log segment after reset" information as a WAL file name,
> instead of logid+segno. Another option would be to print the 64-bit
> segment number, but I think that's worse, because the 64-bit segment
> number is harder to associate with a physical WAL file.
>
> So I think we should change pg_resetxlog -l option to take a WAL file
> name as argument, and fix pg_upgrade accordingly.

The only thing pg_upgrade does with the tli/logid/segno combo, AFAICT,
is pass it back to pg_resetxlog -l, so this plan seems reasonable.

--
Álvaro Herrera <alvherre(at)commandprompt(dot)com>
The PostgreSQL Company - Command Prompt, Inc.
PostgreSQL Replication, Consulting, Custom Development, 24x7 support

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