Re: speed up a logical replica setup

On Mon, Feb 21, 2022, at 8:28 PM, Andres Freund wrote:
> I think the system identifier should also be changed, otherwise you can way
> too easily get into situations trying to apply WAL from different systems to
> each other. Not going to end well, obviously.
Good point.

> > This tool does not take a base backup. It can certainly be included later.
> > There is already a tool do it: pg_basebackup.
>
> It would make sense to allow to call pg_basebackup from the new tool. Perhaps
> with a --pg-basebackup-parameters or such.
Yeah. I'm planning to do that in a near future. There are a few questions in my
mind. Should we call the pg_basebackup directly (like
pglogical_create_subscriber does) or use a base backup machinery to obtain the
backup? If we choose the former, it should probably sanitize the
--pg-basebackup-parameters to allow only a subset of the command-line options
(?). AFAICS the latter requires some refactors in the pg_basebackup code --
e.g. expose at least one function (BaseBackup?) that accepts a struct of
command-line options as a parameter and returns success/failure. Another
possibility is to implement a simple BASE_BACKUP command via replication
protocol. The disadvantages are: (a) it could duplicate code and (b) it might
require maintenance if new options are added to the BASE_BACKUP command.

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