On Wed, Apr 20, 2005 at 07:33:54PM -0400, Tom Lane wrote:
> "Jim C. Nasby" <decibel@decibel.org> writes:
> > In a nutshell, my idea is to use the normal transactional/XID code to
> > relocate tuples in the heap. Think of doing an UPDATE field=field if you
> > could tell update what page to put the new tuple on. Using this
> > mechanism, you can move tuples from the end of the heap to pages that
> > have free space on them. The dead tuples at the end of the heap could
> > then be vacuumed conventionally, and completely empty pages removed by
> > that vacuum.
>
> How exactly is this different from what happens now, assuming that you
> didn't run out of FSM?
In the case of cluster I think it's quite different, as cluster
currently re-writes the heap from scratch, no?
I'm not sure how different it is from vacuum full, though the main idea
is that instead of locking the table you instead work in smaller pieces
and don't block anything other than other updates.
--
Jim C. Nasby, Database Consultant decibel@decibel.org
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