Re: [HACKERS] Zeroing damaged pages

Tom Lane wrote:
> Bruce Momjian <pgman@candle.pha.pa.us> writes:
> >> On Thu, 2006-02-23 at 11:54 -0500, Tom Lane wrote:
> >>> Hmm .... it'd probably be a good idea to force zero_damaged_pages OFF in
> >>> the autovac subprocess.  That parameter is only intended for interactive
> >>> use --- as you say, autovac would be a rather nasty loose cannon if it
> >>> fired up with this parameter ON.
>
> > I am wondering if we should prevent autovac from running if
> > zero_damaged_pages is set in postgresql.conf.
>
> What's wrong with just turning it off locally in the autovac process?
>
> If the admin prefers autovac not run at all while he's fooling around,
> he can disable it in postgresql.conf (or perhaps even better, run in
> single-user mode).  But I don't think it's appropriate to force that
> decision on him.

Done.

--
  Bruce Momjian   http://candle.pha.pa.us
  SRA OSS, Inc.   http://www.sraoss.com

  + If your life is a hard drive, Christ can be your backup. +
Index: src/backend/postmaster/autovacuum.c
===================================================================
RCS file: /cvsroot/pgsql/src/backend/postmaster/autovacuum.c,v
retrieving revision 1.12
diff -c -c -r1.12 autovacuum.c
*** src/backend/postmaster/autovacuum.c    5 Mar 2006 15:58:35 -0000    1.12
--- src/backend/postmaster/autovacuum.c    6 Mar 2006 05:10:23 -0000
***************
*** 125,130 ****
--- 125,133 ----
      if (!AutoVacuumingActive())
          return 0;

+     /* Even if zero_damaged_pages is true, we don't want autovacuum zeroing. */
+     zero_damaged_pages = false;
+
      /*
       * Do nothing if too soon since last autovacuum exit.  This limits how
       * often the daemon runs.  Since the time per iteration can be quite