Re: HOT patch, missing things
| От | Pavan Deolasee |
|---|---|
| Тема | Re: HOT patch, missing things |
| Дата | |
| Msg-id | 2e78013d0708212359jc275a16w6c6c4fdc1a0a4369@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: HOT patch, missing things (Gregory Stark <stark@enterprisedb.com>) |
| Список | pgsql-hackers |
On 8/14/07, Gregory Stark <stark@enterprisedb.com> wrote:
I agree here. As a first step, may be can address the heap space usage
statistics and then take up index stats separately. Index bloat would carry
a different weight in triggering autovacuum.
I shall code up a patch which tracks the dead space in the heap and
trigger autovac based on that.
Thanks,
Pavan
"Tom Lane" <tgl@sss.pgh.pa.us> writes:
>
> Doesn't this design completely fail to take index bloat into account?
> Repairing heap fragmentation does not reduce the need for VACUUM to work
> on the indexes.
Index bloat is a bit of an open issue already. Because page splits already
prune any LP_DELETEd pointers any busy index keys will be pruned already.
However any index keys which have not been the subject of an index lookup --
and that includes keys which are only accessed by bitmap-index-scans -- won't
be pruned.
So we don't really know how much bloat is currently in an index. Perhaps we
need a new statistic which gets updated whenever a page split prunes
LP_DELETEd pointers (or perhaps when LP_DELETE is set?).
I agree here. As a first step, may be can address the heap space usage
statistics and then take up index stats separately. Index bloat would carry
a different weight in triggering autovacuum.
I shall code up a patch which tracks the dead space in the heap and
trigger autovac based on that.
Pavan
--
Pavan Deolasee
EnterpriseDB http://www.enterprisedb.com
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