| From: | Alvaro Herrera <alvherre(at)commandprompt(dot)com> |
|---|---|
| To: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
| Cc: | Csaba Nagy <nagy(at)ecircle-ag(dot)com>, "Matthew T(dot) O'Connor" <matthew(at)zeut(dot)net>, Christopher Browne <cbbrowne(at)acm(dot)org>, postgres hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Automatic free space map filling |
| Date: | 2006-03-03 15:05:17 |
| Message-ID: | 20060303150517.GC5865@surnet.cl |
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| Lists: | pgsql-hackers |
Bruce Momjian wrote:
> Alvaro Herrera wrote:
> > Csaba Nagy wrote:
> >
> > > Now when the queue tables get 1000 times dead space compared to their
> > > normal size, I get performance problems. So tweaking vacuum cost delay
> > > doesn't buy me anything, as not vacuum per se is the performance
> > > problem, it's long run time for big tables is.
> >
> > So for you it would certainly help a lot to be able to vacuum the first
> > X pages of the big table, stop, release locks, create new transaction,
> > continue with the next X pages, lather, rinse, repeat.
>
> But what about index clearing? When do you scan each index?
At the end of each iteration (or earlier, depending on
maintenance_work_mem). So for each iteration you would need to scan the
indexes.
Maybe we could make maintenance_work_mem be the deciding factor; after
scanning the indexes, do the release/reacquire locks cycle.
--
Alvaro Herrera http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.
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