| From: | Josh Berkus <josh(at)agliodbs(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | "Tambet Matiisen" <t(dot)matiisen(at)aprote(dot)ee>, "Bill Chandler" <billybobc1210(at)yahoo(dot)com>, "pgsql-perform" <pgsql-performance(at)postgresql(dot)org> |
| Subject: | Re: Question on REINDEX |
| Date: | 2005-04-19 17:56:16 |
| Message-ID: | 200504191056.16688.josh@agliodbs.com |
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| Thread: | |
| Lists: | pgsql-performance |
Tom,
> Not at all. What it says is that you expect 100% of the pages to have
> useful amounts of free space, which is a *much* weaker criterion.
Hmmm. Good point.
This seems to be another instance where my rule-of-thumb was based on false
logic but nevertheless arrived at correct numbers. I've seldom, if ever, set
FSM_pages above 50% of the pages in the active database ... and never run
out.
Hmmmm .... actually, it seems like, if you are vacuuming regularly, you only
*do* need to track pages that have been touched by DELETE or UPDATE. Other
pages would have already been vacuumed and not have any useful free space
left. Yes?
--
--Josh
Josh Berkus
Aglio Database Solutions
San Francisco
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