| From: | "Scott Marlowe" <smarlowe(at)qwest(dot)net> |
|---|---|
| To: | wespvp(at)syntegra(dot)com |
| Cc: | "Postgres List" <pgsql-general(at)postgresql(dot)org> |
| Subject: | Re: max_fsm_pages |
| Date: | 2004-07-01 21:00:24 |
| Message-ID: | 1088715623.14882.6.camel@localhost.localdomain |
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| Thread: | |
| Lists: | pgsql-general |
On Thu, 2004-07-01 at 11:45, wespvp(at)syntegra(dot)com wrote:
> If max_fsm_pages is too small and I have space not reclaimed by vacuum, if I
> increase max_fsm_pages and restart postmaster, will the next VACUUM ANALYZE
> relcaim all overlooked pages or must I do a VACUUM FULL?
Let's say you have a table with 1,000 rows, but you've deleted 1,000,000
over the past year, and most of those are unclaimed. Regular vacuum
will put those 900,000 odd pages into the FSM, and the database can use
them. However, scans on this table will still be mostly reading empty
space.
So, to collapse the table back down to something reasonable, you'll need
to do a vacuum full, then regular vacuums should keep things tight from
then on.
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