Lincoln Yeoh <lyeoh(at)pop(dot)jaring(dot)my> writes:
> Why do I need to issue two or three or even more vacuums before the tables
> reach their fully cleaned sizes and states?
I seem to recall having noticed that there are corner cases where
VACUUM FULL doesn't achieve all the packing you might expect, and another
VACUUM FULL will accomplish more. Don't recall the details, but you
might find something if you grovel through the code or the pghackers
archives.
regards, tom lane