From: | Bernd Helmle <bernd(dot)helmle(at)oopsware(dot)de> |
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To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: Automatic free space map filling |
Date: | 2006-03-01 20:18:29 |
Message-ID: | 20060301201828.GB26934@sparkey.oopsware.intra |
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Lists: | pgsql-hackers |
On Wed, Mar 01, 2006 at 12:41:01PM -0500, Tom Lane wrote:
> Peter Eisentraut <peter_e(at)gmx(dot)net> writes:
> > Tom Lane wrote:
> >> How does an optimistic FSM entry avoid the need to run vacuum?
>
> > It ensures that all freed tuples are already in the FSM.
>
> That has nothing to do with it, because the space isn't actually free
> for re-use until vacuum deletes the tuple.
>
Hmm, but couldn't such an opportunistic approach be used for another leightweight VACUUM mode in such a
way, that VACUUM could look at a special "Hot Spot" queue, which represents potential candidates for
freeing? Let's call it a 2-phase VACUUM....this would avoid a long running VACUUM run on big tables,
e.g. when tuples gets updated (or deleted) frequently. Just an idea...
Bernd
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