Re: Autovacuum and OldestXmin

On Fri, 2007-11-23 at 01:14 -0500, Tom Lane wrote:
> Simon Riggs <simon(at)2ndquadrant(dot)com> writes:
> > That's a killer reason, I suppose. I was really trying to uncover what
> > the thinking was, so we can document it. Having VACUUM ignore it
> > completely seems wrong.
>
> What you seem to be forgetting is that VACUUM is charged with cleaning
> out LP_DEAD tuples, which HOT cannot do. And the page header fields are
> set (quite properly so) with HOT's interests in mind not VACUUM's.

OK, thanks.

Me getting confused about HOT might cause a few chuckles and it does
with me also. You didn't sit through the months of detailed discussions
of all the many possible ways of doing it (granted all were flawed in
some respect), so I figure I will need to forget those before I
understand the one exact way of doing it that has been committed.
Anyway, thanks for keeping me on track and (again) kudos to Pavan and
team.

--
Simon Riggs
2ndQuadrant http://www.2ndQuadrant.com