Re: Standalone synchronous master

On Jan11, 2014, at 18:53 , Andres Freund <andres@2ndquadrant.com> wrote:
> On 2014-01-11 18:28:31 +0100, Florian Pflug wrote:
>> Hm, I was about to suggest that you can set statement_timeout before
>> doing COMMIT to limit the amount of time you want to wait for the
>> standby to respond. Interestingly, however, that doesn't seem to work,
>> which is weird, since AFAICS statement_timeout simply generates a
>> query cancel requester after the timeout has elapsed, and cancelling
>> the COMMIT with Ctrl-C in psql *does* work.
> 
> I think that'd be a pretty bad API since you won't know whether the
> commit failed or succeeded but replication timed out. There very well
> might have been longrunning constraint triggers or such taking a long
> time.

You could still distinguish these cases because the COMMIT would succeed
with a WARNING if the timeout elapses while waiting for the standby, just
as it does for query cancellations already.

I'm not saying that this is a great API, though - I brought it up only
because I accepting cancellation requests but ignoring timeouts seems
a bit inconsistent to me.

best regards,
Florian Pflug