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

On Sun, Jun 07, 2020 at 10:07:19AM +0200, Fabien COELHO wrote:
> Hello Justin,
> > Rebased onto 7b48f1b490978a8abca61e9a9380f8de2a56f266 and renumbered OIDs.

Rebased again on whatever broke func.sgml.

> pg_stat_file() and pg_stat_dir_files() now return a char type, as well as
> the function which call them, but the documentation does not seem to say
> that it is the case.

Fixed, thanks

> I must admit that I'm not a fan on the argument management of
> pg_ls_dir_metadata and pg_ls_dir_metadata_1arg and others. I understand that
> it saves a few lines though, so maybe let it be.

I think you're saying that you don't like the _1arg functions, but they're
needed to allow the regression tests to pass:

| * note: this wrapper is necessary to pass the sanity check in opr_sanity,
| * which checks that all built-in functions that share the implementing C
| * function take the same number of arguments

> There is a comment in pg_ls_dir_files which talks about pg_ls_dir.
>
> Could pg_ls_*dir functions C implementations be dropped in favor of a pure
> SQL implementation, like you did with recurse?

I'm still waiting to hear feedback from a commiter if this is a good idea to
put this into the system catalog. Right now, ts_debug is the only nontrivial
function.

> If so, ISTM that pg_ls_dir_files() could be significantly simplified by
> moving its filtering flag to SQL conditions on "type" and others. That could
> allow not to change the existing function output a keep the "isdir" column
> defined as "type = 'd'" where it was used previously, if someone complains,
> but still have the full capability of "ls". That would also allow to drop
> the "*_1arg" hacks. Basically I'm advocating having 1 or 2 actual C
> functions, and all other variants managed at the SQL level.

You want to get rid of the 1arg stuff and just have one function.

I see your point, but I guess the C function would still need to accept a
"missing_ok" argument, so we need two functions, so there's not much utility in
getting rid of the "include_dot_dirs" argument, which is there for consistency
with pg_ls_dir.

Conceivably we could 1) get rid of pg_ls_dir, and 2) get rid of the
include_dot_dirs argument and 3) maybe make "missing_ok" a required argument;
and, 4) get rid of the C wrapper functions, and replace with a bunch of stuff
like this:

SELECT name, size, access, modification, change, creation, type='d' AS isdir
FROM pg_ls_dir_metadata('pg_wal') WHERE substring(name,1,1)!='.' AND type!='d';

Where the defaults I changed in this patchset still remain to be discussed:
with or without metadata, hidden files, dotdirs.

As I'm still waiting for committer feedback on the first 10 patches, so not
intending to add more.

--
Justin