Re: An attempt to avoid locally-committed-but-not-replicated-to-standby-transactions in synchronous replication

On Tue, May 10, 2022 at 5:55 PM Andrey Borodin <x4mmm(at)yandex-team(dot)ru> wrote:
>
> > 10 мая 2022 г., в 12:59, Bharath Rupireddy <bharath(dot)rupireddyforpostgres(at)gmail(dot)com> написал(а):
> >
> > If okay, I can make the GUC behave this way - value 0 existing
> > behaviour i.e. no wait for sync repl ack, just process query cancels
> > and proc die interrupts immediately; value -1 wait unboundedly for the
> > ack; value > 0 wait for specified milliseconds for the ack.
> +1 if we make -1 and 0 only valid values.
>
> > query cancels or proc die interrupts
>
> Please note, that typical HA tool would need to handle query cancels and proc die interrupts differently.

Agree.

> When the network is partitioned and somewhere standby is promoted you definitely want infinite wait for cancels.

When standby is promoted, no point the old primary waiting forever for
ack assuming we are going to discard it.

> Yet once upon a time you want to shutdown postgres without coredump - thus proc die needs to be processed.

I think users can still have the flexibility to set the right amounts
of time to process cancel and proc die interrupts.

IMHO, the GUC can still have 0, -1 and value > 0 in milliseconds, let
the users decide on what they want. Do you see any problems with this?

Thoughts?

Regards,
Bharath Rupireddy.