Re: Catalog/Metadata consistency during changeset extraction from wal

On Mon, Jun 25, 2012 at 01:50:54PM -0500, Kevin Grittner wrote:
> Andres Freund <andres(at)2ndquadrant(dot)com> wrote:
>
> > I am not sure were going to get all that into 9.3.
>
> Sure, that was more related to why I was questioning how much these
> use cases even *could* integrate -- whether it even paid to
> *consider* these use cases at this point. Responses from Robert and
> you have pretty much convinced me that I was being overly
> pessimistic on that.
>
> 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?

Cheers,
David.
--
David Fetter <david(at)fetter(dot)org> http://fetter.org/
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