Re: tracking commit timestamps

On 2014-11-11 17:09:54 +0000, Simon Riggs wrote:
> On 11 November 2014 16:19, Andres Freund <andres(at)2ndquadrant(dot)com> wrote:
> > On 2014-11-11 16:10:47 +0000, Simon Riggs wrote:
> >> On 4 November 2014 08:23, Andres Freund <andres(at)2ndquadrant(dot)com> wrote:
> >>
> >> >> 6) Shouldn't any value update of track_commit_timestamp be tracked in
> >> >> XLogReportParameters? That's thinking about making the commit timestamp
> >> >> available on standbys as well..
> >> >
> >> > Yes, it should.
> >>
> >> Agree committs should be able to run on standby, but it seems possible
> >> to do that without it running on the master.
> >
> > I don't think that's realistic. It requires WAL to be written in some
> > cases, so that's not going to work. I also don't think it's a
> > particularly interesting ability?
>
> OK, so we are saying commit timestamp will NOT be available on Standbys.

Hm? They should be available - xact.c WAL replay will redo the setting
of the timestamps and explicitly overwritten timestamps will generate
their own WAL records. What I mean is just that you can't use commit
timestamps without also using it on the primary.

Greetings,

Andres Freund

--
Andres Freund http://www.2ndQuadrant.com/
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