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Re: pg_start_backup and pg_stop_backup Re: Re: [COMMITTERS] pgsql: Make CheckRequiredParameterValues() depend upon correct

From: Bruce Momjian <bruce(at)momjian(dot)us>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>, Simon Riggs <simon(at)2ndquadrant(dot)com>, Fujii Masao <masao(dot)fujii(at)gmail(dot)com>, Alvaro Herrera <alvherre(at)commandprompt(dot)com>, Josh Berkus <josh(at)agliodbs(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: pg_start_backup and pg_stop_backup Re: Re: [COMMITTERS] pgsql: Make CheckRequiredParameterValues() depend upon correct
Date: 2010-04-30 17:58:08
Message-ID: 201004301758.o3UHw8E25808@momjian.us (view raw or flat)
Thread:
Lists: pgsql-hackers
Robert Haas wrote:
> On Fri, Apr 30, 2010 at 1:39 PM, Bruce Momjian <bruce(at)momjian(dot)us> wrote:
> > Robert Haas wrote:
> >> On Fri, Apr 30, 2010 at 12:22 PM, Bruce Momjian <bruce(at)momjian(dot)us> wrote:
> >> > Tom Lane wrote:
> >> >> Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com> writes:
> >> >> > Tom Lane wrote:
> >> >> >> If you aren't archiving then there's no guarantee that you'll still have
> >> >> >> a continuous WAL series starting from the start of the backup.
> >> >>
> >> >> > I wasn't really thinking of this use case, but you could set
> >> >> > wal_keep_segments "high enough".
> >> >>
> >> >> Ah. ?Okay, that seems like a workable approach, at least for people with
> >> >> reasonably predictable WAL loads. ?We could certainly improve on it
> >> >> later to make it more bulletproof, but it's usable now --- if we relax
> >> >> the error checks.
> >> >>
> >> >> (wal_keep_segments can be changed without restarting, right?)
> >> >
> >> > Should we allow -1 to mean "keep all segments"?
> >>
> >> If that's what you want to do, use archive_mode.
> >
> > Uh, I assume that will require me to store the WAL files somewhere else,
> > rather than keeping them in /pg_xlog, which I thought was the goal. ?Am
> > I missing something?
> 
> Well, one of us is.  Why would you want to retain all of your WAL logs
> in pg_xlog forever?

Well, this email thread mentioned a case where you needed to increase
wal_keep_segments to a sufficiently-high value, and of course figuring
out such a value is harder than just having a way of turning off
recycling with -1.

-- 
  Bruce Momjian  <bruce(at)momjian(dot)us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

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Next:From: Simon RiggsDate: 2010-04-30 18:08:25
Subject: Re: pg_start_backup and pg_stop_backup Re: Re: [COMMITTERS] pgsql: Make CheckRequiredParameterValues() depend upon correct
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Subject: Re: pg_start_backup and pg_stop_backup Re: Re: [COMMITTERS] pgsql: Make CheckRequiredParameterValues() depend upon correct

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