Re: Refactoring of compression options in pg_basebackup

On Mon, Dec 20, 2021 at 7:43 PM Michael Paquier <michael(at)paquier(dot)xyz> wrote:
> Yeah, consistency would be good. For the client-side compression of
> LZ4, we have shaped things around the existing --compress option, and
> there is 6f164e6 that offers an API to parse that at option-level,
> meaning less custom error strings. I'd like to think that splitting
> the compression level and the compression method is still the right
> choice, except if --server-compression combined with a client-side
> compression is a legal combination. This would not really make sense,
> though, no? So we'd better block this possibility from the start?

Right. It's blocked right now, but Tushar noticed on the other thread
that the error message isn't as good as it could be, so I'll improve
that a bit. Still the issue wasn't overlooked.

> > If they don't decompress the backup and run pg_verifybackup on it then
> > I'm not sure how much they help. Yet, I don't know how to do that
> > portably.
>
> They help in checking that an environment does not use a buggy set of
> GZIP, at least. Using pg_verifybackup on a base backup with
> --format='t' could be tweaked with $ENV{TAR} for the tarballs
> generation, for example, as we do in some other tests. Option sets
> like "xvf" or "zxvf" should be rather portable across the buildfarm,
> no? I'd like to think that this is not a requirement for adding
> checks in the compression path, as a first step, though, but I agree
> that it could be extended more.

Oh, well, if we have a working tar available, then it's not so bad. I
was thinking we couldn't really count on that, especially on Windows.

--
Robert Haas
EDB: http://www.enterprisedb.com