Re: pgsql: Fix pg_basebackup with in-place tablespaces.

On Wed, Mar 16, 2022 at 10:28 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> David Steele <david@pgmasters.net> writes:
> > On 3/14/22 19:31, Thomas Munro wrote:
> >> Fix pg_basebackup with in-place tablespaces.
>
> > Perhaps I'm being picky, but seems like this logic should be wrapped in:
> > if (allow_in_place_tablespaces)
> > {
> >      <...>
> > }
> > I worry about strange effects when this GUC is not enabled.
>
> What would happen if someone created an in-place tablespace and
> then turned off the GUC?

Then it would break with unhelpful error messages.  I suppose we could
error out explicitly, "in-place tablespace detected, but
allow_in_place_tablespaces not enabled".  I'm not sure why we should
suddenly choose to enforce that *here* though.