Re: Improvement of procArray.xmin for VACUUM - Mailing list pgsql-patches

From Bruce Momjian
Subject Re: Improvement of procArray.xmin for VACUUM
Date
Msg-id 200703271417.l2REHf012470@momjian.us
Whole thread Raw
In response to Re: Improvement of procArray.xmin for VACUUM  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-patches
Tom Lane wrote:
> Bruce Momjian <bruce@momjian.us> writes:
> > Tom Lane wrote:
> >> Bruce Momjian <bruce@momjian.us> writes:
> >>> Well, my secondary addition was to start MyProc->xmin with the current
> >>> xid counter, rather than your own xid.
> >>
> >> Don't tell me you seriously believe that would work.
>
> > I do.  Please tell me why it will not.
>
> You can't have GlobalXmin greater than your own xid, else log space
> (particularly pg_subtrans) may be recycled too soon.

OK, so maybe GlobalXmin would have to be split into two new variables
that control log space and dead-row detection separately.

--
  Bruce Momjian  <bruce@momjian.us>          http://momjian.us
  EnterpriseDB                               http://www.enterprisedb.com

  + If your life is a hard drive, Christ can be your backup. +

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