Re: speed up a logical replica setup

On Thu, Jan 11, 2024 at 7:59 AM Euler Taveira <euler(at)eulerto(dot)com> wrote:
>
> On Wed, Jan 10, 2024, at 1:33 AM, Shlok Kyal wrote:
>
> Here the standby node would be waiting for the 'consistent_lsn' wal
> during recovery but this wal will not be present on standby if no
> physical replication is setup. Hence the command will be waiting
> infinitely for the wal.
>
>
> Hmm. Some validations are missing.
>
> To solve this added a timeout of 60s for the recovery process and also
> added a check so that pg_subscriber would give a error when it called
> for node which is not in physical replication.
> Have attached the patch for the same. It is a top-up patch of the
> patch shared by Euler at [1].
>
>
> If the user has a node that is not a standby and it does not set the GUCs to
> start the recovery process from a backup, the initial setup is broken. (That's
> the case you described.) A good UI is to detect this scenario earlier.
> Unfortunately, there isn't a reliable and cheap way to do it. You need to start
> the recovery and check if it is having some progress. (I don't have a strong
> opinion about requiring a standby to use this tool. It would reduce the
> complexity about checking if the setup has all requirements to run this tool.)
>

Right, such a check will reduce some complexity. So, +1 for the check
as proposed by Shlok. Also, what are your thoughts on a timeout during
the wait? I think it is okay to wait for 60s by default but there
should be an option for users to wait for longer.

--
With Regards,
Amit Kapila.