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

Robert Haas wrote:
> On Fri, Apr 30, 2010 at 1:39 PM, Bruce Momjian <bruce@momjian.us> wrote:
> > Robert Haas wrote:
> >> On Fri, Apr 30, 2010 at 12:22 PM, Bruce Momjian <bruce@momjian.us> wrote:
> >> > Tom Lane wrote:
> >> >> Heikki Linnakangas <heikki.linnakangas@enterprisedb.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@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com