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

On Tue, Apr 2, 2024 at 2:47 PM Andy Fan <zhihuifan1213(at)163(dot)com> wrote:
> Bharath Rupireddy <bharath(dot)rupireddyforpostgres(at)gmail(dot)com> writes:
>
> > On Tue, Apr 2, 2024 at 3:41 PM Kartyshov Ivan
> > <i(dot)kartyshov(at)postgrespro(dot)ru> wrote:
> >>
> >> 8 years, we tried to add this feature, and now we suggest the best way
> >> for this feature is to commit the minimal version first.
> >
> > Just curious, do you or anyone else have an immediate use for this
> > function? If yes, how are they achieving read-after-write-consistency
> > on streaming standbys in their application right now without a
> > function like this?
>
> The link [1] may be helpful and I think the reason there is reasonable
> to me.
>
> Actually we also disucss how to make sure the "read your writes
> consistency" internally, and the soluation here looks good to me.
>
> Glad to know that this patch will be committed very soon.
>
> [1]
> https://www.postgresql.org/message-id/CAPpHfdtuiL1x4APTs7u1fCmxkVp2-ZruXcdCfprDMdnOzvdC%2BA%40mail.gmail.com

Thank you for your feedback.

I also can confirm that a lot of users would be very happy to have
"read your writes consistency" and ready to do something to achieve
this at an application level. However, they typically don't know what
exactly they need.

So, blogging about pg_wal_replay_wait() and spreading words about it
at conferences would be highly appreciated.

------
Regards,
Alexander Korotkov