| From: | Bruce Momjian <bruce(at)momjian(dot)us> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Simon Riggs <simon(at)2ndquadrant(dot)com>, Heikki Linnakangas <heikki(at)enterprisedb(dot)com>, PostgreSQL-patches <pgsql-patches(at)postgresql(dot)org> |
| Subject: | Re: Improvement of procArray.xmin for VACUUM |
| Date: | 2007-03-27 14:17:41 |
| Message-ID: | 200703271417.l2REHf012470@momjian.us |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-patches |
Tom Lane wrote:
> Bruce Momjian <bruce(at)momjian(dot)us> writes:
> > Tom Lane wrote:
> >> Bruce Momjian <bruce(at)momjian(dot)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(at)momjian(dot)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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