Re: Dead Space Map for vacuum

"Simon Riggs" <simon@2ndquadrant.com> writes:
> On Fri, 2006-12-29 at 10:49 -0500, Tom Lane wrote:
>> Counterexample: table in which all tuples exceed half a page.

> Current FSM code will ignore those too, if they are less than the
> average size of the tuple so far requested. Thats a pretty wierd
> counterexample, even if it is a case that needs handling.

Better read it again.  The number that's passed to the FSM is the
free space *after* vacuuming, which in this scenario will be
BLCKSZ-less-page-header.  This case is not broken now, but it will
be if we adopt your proposal.
        regards, tom lane