Re: PostgreSQL clustering VS MySQL clustering

Tatsuo Ishii <t-ishii@sra.co.jp> writes:
> Probably VACUUM works well for small to medium size tables, but not
> for huge ones. I'm considering about to implement "on the spot
> salvaging dead tuples".

That's impossible on its face, except for the special case where the
same transaction inserts and deletes a tuple.  In all other cases, the
transaction deleting a tuple cannot know whether it will commit.

            regards, tom lane