Re: Enabling Checksums

Tom Lane <tgl@sss.pgh.pa.us>

From: Tom Lane <tgl@sss.pgh.pa.us>

To: Greg Stark <stark@mit.edu>

Cc: Florian Pflug <fgp@phlo.org>, Bruce Momjian <bruce@momjian.us>, Ants Aasma <ants@cybertec.at>, Andres Freund <andres@2ndquadrant.com>, Jeff Davis <pgsql@j-davis.com>, Heikki Linnakangas <hlinnakangas@vmware.com>, Simon Riggs <simon@2ndquadrant.com>, Greg Smith <greg@2ndquadrant.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>

Date: 2013-04-17T17:22:01Z

Lists: pgsql-hackers

Greg Stark <stark@mit.edu> writes:
> On Wed, Apr 17, 2013 at 4:28 PM, Florian Pflug <fgp@phlo.org> wrote:
>> Is there any way we can change the checksum algorithm in 9.4
>> *without* breaking pg_upgrade?

> Personally I think we're going to need a solution for page format
> changes someday eventually....

> What advantages are we postponing now to avoid it?

Um, other than the ability to make a release?

We aren't going to hold up 9.3 until that particular bit of pie in the
sky lands.  Indeed I don't expect to see it available in the next couple
years either.  When we were looking at that seriously, two or three
years ago, arbitrary page format changes looked *hard*.

The idea of bumping the page format version number to signal a checksum
algorithm change might work though.

			regards, tom lane