Re: 16-bit page checksums for 9.2 - Mailing list pgsql-hackers

From Alvaro Herrera
Subject Re: 16-bit page checksums for 9.2
Date
Msg-id 1330552331-sup-29@alvh.no-ip.org
Whole thread Raw
In response to Re: 16-bit page checksums for 9.2  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: 16-bit page checksums for 9.2  (Jim Nasby <jim@nasby.net>)
List pgsql-hackers
Excerpts from Tom Lane's message of mié feb 29 18:34:27 -0300 2012:
>
> Robert Haas <robertmhaas@gmail.com> writes:
> > On Wed, Feb 29, 2012 at 2:33 PM, Heikki Linnakangas
> > <heikki.linnakangas@enterprisedb.com> wrote:
> >> The utility would run in the old cluster before upgrading, so the the flag
> >> would have to be present in the old version. pg_upgrade would check that the
> >> flag is set, refusing to upgrade if it isn't, with an error like "please run
> >> pre-upgrade utility first".
>
> > I find that a pretty unappealing design; it seems to me it'd be much
> > easier to make the new cluster cope with everything.
>
> Easier for who?  I don't care for the idea of code that has to cope with
> two page formats, or before long N page formats, because if we don't
> have some mechanism like this then we will never be able to decide that
> an old data format is safely dead.

.. in fact this is precisely what killed Zdenek Kotala's idea of
upgrading.

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


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