Horton

Re: heap vacuum & cleanup locks

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Simon Riggs <simon@2ndquadrant.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2011-11-09T22:18:04Z
Lists: pgsql-hackers

Commits

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  1. Make VACUUM avoid waiting for a cleanup lock, where possible.

Robert Haas <robertmhaas@gmail.com> writes:
> As for what to do about all this, I think Tom's idea would work for
> good tuples, but the current freezing code can't handle dead tuples;
> it counts on those having been already removed.

I have not gone back to look at the code, but are you worried about the
fact that it doesn't consider replacing xmax with FrozenTransactionId?
Surely we could do that if we wanted.  It just never seemed necessary
before --- but if vacuum is to be allowed to punt repeatedly on the same
page, maybe we do need to cover the case.

			regards, tom lane