Re: Simplifying "standby mode"

Simon Riggs <simon@2ndquadrant.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.
        regards, tom lane