Re: Question on REINDEX - Mailing list pgsql-performance

From Josh Berkus
Subject Re: Question on REINDEX
Date
Msg-id 200504191056.16688.josh@agliodbs.com
Whole thread Raw
In response to Re: Question on REINDEX  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: Question on REINDEX  (Tom Lane <tgl@sss.pgh.pa.us>)
List 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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