Re: WAL-based allocation of XIDs is insecure

Zeugswetter Andreas SB <ZeugswetterA@wien.spardat.at> wrote:
>
> In short I do not think that the current implementation of
> "physical log" does what it was intended to do :-(

Hm, wasn't it handling non-atomic disk writes, Andreas?
And for what else "physical log" could be used?

The point was - copy entire page content on first after
checkpoint modification, so on recovery first restore page
to consistent state, so all subsequent logged modifications
could be applied without fear about page inconsistency.

Now, why should we log page as it was *before* modification?
We would log modification anyway (yet another log record!) and
would apply it to page, so result would be the same as now when
we log page after modification - consistent *modifyed* page.

?

Vadim