Re: pgsql: Allow time delayed standbys and recovery

Thom Brown <thom@linux.com>

From: Thom Brown <thom@linux.com>
To: Simon Riggs <simon@2ndquadrant.com>
Cc: pgsql-committers <pgsql-committers@postgresql.org>
Date: 2014-02-26T13:07:51Z
Lists: pgsql-hackers
On 19 December 2013 19:33, Simon Riggs <simon@2ndquadrant.com> wrote:

> On 19 December 2013 19:19, Thom Brown <thom@linux.com> wrote:
> > On 12 December 2013 10:56, Simon Riggs <simon@2ndquadrant.com> wrote:
> >> Allow time delayed standbys and recovery
> >>
> >> Set min_recovery_apply_delay to force a delay in recovery apply for
> commit and
> >> restore point WAL records. Other records are replayed immediately.
> Delay is
> >> measured between WAL record time and local standby time.
> >>
> >> Robert Haas, Fabrízio de Royes Mello and Simon Riggs
> >> Detailed review by Mitsumasa Kondo
> >
> > Could a note be added about the additional disk space requirements for
> > WAL on the standby?  If one is delaying replay, WAL files created over
> > the delayed period will build up in pg_xlog on the standby until
> > they're consumed upon replay, so considerations about storing those
> > additional files will need to be made.  It may otherwise trip up
> > anyone who, say, delays replay by 24 hours in a busy production
> > environment, and finds they have run out of disk space and no longer
> > have a valid standby.
>
> Thanks Thom, good point. I will add a note to the docs.
>

Just a reminder that this note hasn't been added to the docs yet.

-- 
Thom

Commits

  1. docs: Note the recovery_min_apply_delay bloats pg_wal.

  2. Allow time delayed standbys and recovery