Re: Idea for getting rid of VACUUM FREEZE on cold pages

* Tom Lane (tgl@sss.pgh.pa.us) wrote:
> If we were actually going in this direction we'd
> want to write a much better WAL-text-dump tool than we have, and then
> in principle somebody could sanitize the text output before shipping
> it off.  But going through a large volume of data that way could be
> pretty impractical.  Also, we (or at least I) have nearly zip experience
> with trying to debug problems by examining WAL, so it's not real clear
> to me which details might be important.

Just an off-the-wall thought, but, would it be possible to have a tool
which read WAL backwards and compared entries in the WAL against entries
on disk?  I realize that you'd only see one version of a particular
block and then have to skip any updates which are earlier than it, but
it seems like you could cover a pretty large chunk of the recent changes
to the database using this approach..
Thanks,
    Stephen