Re: speed up a logical replica setup

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.)

--
Euler Taveira
EDB https://www.enterprisedb.com/