On Fri, 2010-03-19 at 01:59 +0530, Gokulakannan Somasundaram wrote:
>
> The visibility map itself is already an example of
> compression. If
> visibility information were randomly distributed among tuples,
> the
> visibility map would be nearly useless.
>
>
> I believe it is very difficult to make visibility map update friendly
> without compromising durability. But such a functionality is very
> much wanted in PG still.
Surely the VM is already update-friendly. If you update a tuple in a
page with the visibility bit set, the bit must be unset or you will get
wrong results.
Regards,Jeff Davis
