Re: pg_basebackup behavior on non-existent slot

On Mon, Sep 4, 2017 at 3:21 PM, Jeff Janes <jeff(dot)janes(at)gmail(dot)com> wrote:

>
> If I tell pg_basebackup to use a non-existent slot, it immediately reports
> an error. And then it exits with an error, but only after streaming the
> entire database contents.
>
> If you are doing this interactively and are on the ball, of course, you
> can hit ctrl-C when you see the error message.
>
> I don't know if this is exactly a bug, but it seems rather unfortunate.
>

I think that should qualify as a bug.

In 10 it will automatically create a transient slot in this case, but there
might still be a case where you can provoke this.

> Should the parent process of pg_basebackup be made to respond to SIGCHLD?
> Or call waitpid(bgchild, &status, WNOHANG) in some strategic loop?
>

I think it's ok to just call waitpid() -- we don't need to react super
quickly, but we should react. And we should then exit the main process with
an error before actually streaming everything.

--
Magnus Hagander
Me: https://www.hagander.net/ <http://www.hagander.net/>
Work: https://www.redpill-linpro.com/ <http://www.redpill-linpro.com/>