Re: 16-bit page checksums for 9.2

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.
        regards, tom lane