Re: Catalog/Metadata consistency during changeset extraction from wal

On Tue, Jun 26, 2012 at 05:05:27PM -0500, Kevin Grittner wrote:
> David Fetter <david@fetter.org> wrote:
> > On Mon, Jun 25, 2012 at 01:50:54PM -0500, Kevin Grittner wrote:
>
> >> One fine point regarding before and after images -- if a value
> >> doesn't change in an UPDATE, there's no reason to include it in
> >> both the BEFORE and AFTER tuple images, as long as we have the
> >> null column bitmaps -- or some other way of distinguishing
> >> unchanged from NULL.  (This could be especially important when
> >> the unchanged column was a 50 MB bytea.)
> >
> > How about two bitmaps: one telling which columns are actually
> > there, the other with NULLs?
>
> There are quite a few ways that could be done, but I suspect
> Álvaro's idea is best:
>
> http://archives.postgresql.org/message-id/1340654533-sup-5535@alvh.no-ip.org

Looks great (or at least way better than mine) to me :)

> In any event, it sounds like Andres wants to keep it as simple as
> possible for the moment, and just include both tuples in their
> entirety.  Hopefully that is something which can be revisited before
> the last CF.

I hope so, too...

Cheers,
David.
--
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