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Re: 8.2 Autovacuum BUG ?


  • From: "Mikko Partio" <mpartio(at)gmail(dot)com>
  • To: "Alvaro Herrera" <alvherre(at)commandprompt(dot)com>
  • Cc: "Pallav Kalva" <pkalva(at)livedatagroup(dot)com>, "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-performance(at)postgresql(dot)org
  • Subject: Re: 8.2 Autovacuum BUG ?
  • Date: Fri, 31 Aug 2007 21:31:47 +0300
  • Message-id: <2ca799770708311131r5ae5e3eera66a7cea1fc5917d@mail.gmail.com> <text/plain>

On 8/31/07, Alvaro Herrera <alvherre(at)commandprompt(dot)com> wrote:
>
> Pallav Kalva wrote:
> > Tom Lane wrote:
>
> >> Probably represents freezing of old tuples, which is a WAL-logged
> >> operation as of 8.2.  Is it likely that the data is 200M transactions
> >> old?
> >>
> > If nothing changed on these tables how can it freeze old tuples ?
> > Does it mean that once it reaches 200M transactions it will do the same
> > thing all over again ?
>
> No -- once tuples are frozen, they don't need freezing again (unless
> they are modified by UPDATE or DELETE).
>
>

Off-topic question: the documentation says that XID numbers are 32 bit.
Could the XID be 64 bit when running on a 64 bit platform? That would
effectively prevent wrap-around issues.

Regards

MP


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