| From: | Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com> |
|---|---|
| To: | PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Visibility map, partial vacuums |
| Date: | 2008-11-20 13:29:48 |
| Message-ID: | 4925664C.3090605@enterprisedb.com |
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| Lists: | pgsql-hackers |
I committed the changes to FSM truncation yesterday, that helps with the
truncation of the visibility map as well. Attached is an updated
visibility map patch.
There's two open issues:
1. The bits in the visibility map are set in the 1st phase of lazy
vacuum. That works, but it means that after a delete or update, it takes
two vacuums until the bit in the visibility map is set. The first vacuum
removes the dead tuple, and only the second sees that there's no dead
tuples and sets the bit.
2. Should modify the output of VACUUM VERBOSE to say how many pages were
actually scanned. What other information is relevant, or is no longer
relevant, with partial vacuums.
--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com
| Attachment | Content-Type | Size |
|---|---|---|
| visibilitymap-2.patch | text/x-diff | 48.2 KB |
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