Re: Minimally avoiding Transaction Wraparound in VLDBs

From: Gavin Sherry <swm(at)linuxworld(dot)com(dot)au>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: Minimally avoiding Transaction Wraparound in VLDBs
Date: 2005-09-22 05:52:21
Message-ID: Pine.LNX.4.58.0509221550570.24326@linuxworld.com.au
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On Wed, 31 Aug 2005, Tom Lane wrote:

> BTW ... the original Berkeley papers on Postgres make frequent reference
> to a "vacuum daemon", which seems to be essentially what we're trying to
> build with autovacuum. Does anyone know if the Berkeley implementation
> ever actually had auto vacuuming, or was that all handwaving? If it did
> exist, why was it removed?

Well, I was just poking around the executor and noticed this in
ExecDelete():

/*
* Note: Normally one would think that we have to delete index tuples
* associated with the heap tuple now..
*
* ... but in POSTGRES, we have no need to do this because the vacuum
* daemon automatically opens an index scan and deletes index tuples
* when it finds deleted heap tuples. -cim 9/27/89
*/

So, it seems they must have actually written the vacuum daemon.

Gavin

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