Re: Keepalive for max_standby_delay

Greg Stark <gsstark@mit.edu> writes:
>> Well, if the slave can't keep up, that's a separate problem. �It will
>> not fail to keep up as a result of the transmission mechanism.

> No, I mean if the slave is paused due to a conflict. Does it stop
> reading data from the master or does it buffer it up on disk? If it
> stops reading it from the master then the effect is the same as if the
> slave stopped "requesting" data even if there's no actual request.

The data keeps coming in and getting dumped into the slave's pg_xlog.
walsender/walreceiver are not at all tied to the slave's application
of WAL.  In principle we could have the code around max_standby_delay
notice just how far behind it's gotten and adjust the delay tolerance
based on that; but I think designing a feedback loop for that is 9.1
material.
        regards, tom lane