Re: [HACKERS] make async slave to wait for lsn to be replayed

Greetings,

* Simon Riggs (simon(at)2ndquadrant(dot)com) wrote:
> On 22 January 2018 at 23:21, Stephen Frost <sfrost(at)snowman(dot)net> wrote:
>
> >> It sounds reasonable. I can offer the following version.
> >>
> >> WAIT LSN lsn_number;
> >> WAIT LSN lsn_number TIMEOUT delay;
> >> WAIT LSN lsn_number INFINITE;
> >> WAIT LSN lsn_number NOWAIT;
> >>
> >>
> >> WAIT [token] wait_value [option];
> >>
> >> token - [LSN, TIME | TIMESTAMP | CSN | XID]
> >> option - [TIMEOUT | INFINITE | NOWAIT]
> >>
> >> Ready to listen to your suggestions.
> >
> > There were a few different suggestions made, but somehow this thread
> > ended up in Needs Review again while still having LSNs. I've changed it
> > back to Waiting for Author since it seems pretty unlikely that using LSN
> > is going to be acceptable based on the feedback.
>
> I agree with the need for a separate command rather than a function.
>
> I agree that WAIT LSN is good syntax because this allows us to wait
> for something else in future.
>
> Without having reviewed the patch, I think we want this feature in PG11.

I've also looked back through this and while I understand the up-thread
discussion about having something better than LSN, I don't see any
particular reason to not allow waiting on LSN, so I agree with Simon
that this makes sense to include. There are definite cases it helps
with today and it doesn't block off future work.

As we're closing out the January commitfest, I've moved this to the next
one.

Thanks!

Stephen