"Iain" <[EMAIL PROTECTED]> writes:
>> another  way  to speed up full vacuum?

> Hmmm... a full vacuum may help to re-organize the structure of modified 
> tables, but whether this is significant or not is another matter.

Actually, VACUUM FULL is designed to work nicely for the situation where
a table has say 10% wasted space and you want the wasted space all
compressed out.  When there is a lot of wasted space, so that nearly all
the rows have to be moved to complete the compaction operation, VACUUM
FULL is not a very good choice.  And it simply moves rows around, it
doesn't modify the rows internally; so it does nothing at all to reclaim
space that would have been freed up by DROP COLUMN operations.

CLUSTER is actually a better bet if you want to repack a table that's
suffered a lot of updates or deletions.  In PG 8.0 you might also
consider one of the rewriting variants of ALTER TABLE.

                        regards, tom lane

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