Re: Simplifying "standby mode"

On Mon, 2006-08-07 at 11:37 -0400, Tom Lane wrote:
> Simon Riggs <simon(at)2ndquadrant(dot)com> writes:
> > If we are in standby mode, then rather than ending recovery we go into a
> > wait loop. We poll for the next file, then sleep for 1000 ms, then poll
> > again. When a file arrives we mark a restartpoint each checkpoint.
>
> > We need the standby_mode to signify the difference in behaviour at
> > end-of-logs, but we may not need a parameter of that exact name.
>
> > The piece I have been puzzling over is how to initiate a failover when
> > in standby_mode. I've not come up with a better solution than checking
> > for the existence of a trigger file each time round the next-file wait
> > loop. This would use a naming convention to indicate the port number,
> > allowing us to uniquely identify a cluster on any single server. That's
> > about as portable and generic as you'll get.
>
> The original intention was that all this sort of logic was to be
> external in the recovery_command script. I'm pretty dubious about
> freezing it in the C code when there's not yet an established
> convention for how it should work. I'd kinda like to see a widely
> accepted recovery_command script before we move the logic inside
> the server.

OK, I'll submit a C program called pg_standby so that we have an
approved and portable version of the script, allowing it to be
documented more easily.

--
Simon Riggs
EnterpriseDB http://www.enterprisedb.com