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

On Sun, Apr 12, 2020 at 01:53:40PM +0200, Fabien COELHO wrote:
> About v15, seen as one patch.

Thanks for looking.

> - I'm wondering whether could pg_stat_file call pg_ls_dir_files without
> too much effort? ISTM that the output structure nearly the same. I do
> not like much having one function specialized for files and one for
> directories.

I refactored but not like that. As I mentioned in the commit message, I don't
see a good way to make a function operate on a file when the function's primary
data structure is a DIR*. Do you ? I don't think it should call stat() and
then conditionally branch off to pg_stat_file().

There are two functions because they wrap two separate syscalls, which see as
good, transparent goal. If we want a function that does what "ls -al" does,
that would also be a good example to follow, except that we already didn't
follow it.

/bin/ls first stat()s the path, and then either outputs its metadata (if it's a
file or if -d was specified) or lists a dir. It's essentially a wrapper around
*two* system calls (stat and readdir/getdents).

Maybe we could invent a new pg_ls() which does that, and then refactor existing
code. Or, maybe it would be a SQL function which calls stat() and then
conditionally calls pg_ls_dir if isdir=True (or type='d'). That would be easy
if we merge the commit which outputs all stat fields.

I'm still hoping for confirmation from a committer if this approach is worth
pursuing:

https://www.postgresql.org/message-id/20200310183037.GA29065%40telsasoft.com
https://www.postgresql.org/message-id/20200313131232.GO29065%40telsasoft.com
|Rather than making "recurse into tmpdir" the end goal:
|
| - add a function to show metadata of an arbitrary dir;
| - add isdir arguments to pg_ls_* functions (including pg_ls_tmpdir but not
| pg_ls_dir).
| - maybe add pg_ls_dir_recurse, which satisfies the original need;
| - retire pg_ls_dir (does this work with tuplestore?)
| - profit

--
Justin