Re: pg_ls_tmpdir to show directories and shared filesets (and pg_ls_*)

Greetings,

* Justin Pryzby (pryzby(at)telsasoft(dot)com) wrote:
> On Mon, Nov 23, 2020 at 04:14:18PM -0500, Tom Lane wrote:
> > * I don't think it's okay to change the existing signatures of
> > pg_ls_logdir() et al. Even if you can make an argument that it's
> > not too harmful to add more output columns, replacing pg_stat_file's
> > isdir output with something of a different name and datatype is most
> > surely not OK --- there is no possible way that doesn't break existing
> > user queries.
> >
> > I think possibly a more acceptable approach is to leave these functions
> > alone but add documentation explaining how to get the additional info.
> > You could say things along the lines of "pg_ls_waldir() is the same as
> > pg_ls_dir_metadata('pg_wal') except for showing fewer columns."
>
> On Mon, Nov 23, 2020 at 06:06:19PM -0500, Tom Lane wrote:
> > I'm mostly concerned about removing the isdir output of pg_stat_file().
> > Maybe we could compromise to the extent of keeping that, allowing it
> > to be partially duplicative of a file-type-code output column.
>
> On Tue, Nov 24, 2020 at 11:53:22AM -0500, Stephen Frost wrote:
> > I don't have any particular issue with keeping isdir as a convenience
> > column. I agree it'll now be a bit duplicative but that seems alright.
>
> Maybe we should do what Tom said, and leave pg_ls_* unchanged, but also mark
> them as deprecated in favour of:
> | pg_ls_dir_metadata(dir), dir={'pg_wal/archive_status', 'log', 'pg_wal', 'base/pgsql_tmp'}

Haven't really time to review the patches here in detail right now
(maybe next month), but in general, I dislike marking things as
deprecated. If we don't want to change them and we're happy to continue
supporting them as-is (which is what 'deprecated' really means), then we
can just do so- nothing stops us from that. If we don't think the
current API makes sense, for whatever reason, we can just change that-
there's no need for a 'deprecation period', as we already have major
versions and support each major version for 5 years.

I haven't particularly strong feelings one way or the other regarding
these particular functions. If you asked which way I leaned, I'd say
that I'd rather redefine the functions to make more sense and to be easy
to use for people who would like to use them. I wouldn't object to new
functions to provide that either though. I don't think there's all that
much code or that it's changed often enough to be a big burden to keep
both, but that's more feeling than anything based in actual research at
this point.

Thanks,

Stephen