bug#36714: 27.0.50; Gnus nnmaildir taking long time to recursively visit sub-Maildirs

[Jean Louis <bugs@gnu.support>]

* Eric Abrahamsen <eric@ericabrahamsen.net> [2019-07-19 19:24]:
> > Thank you for helping. Yet it is not usable for
> > me. I have too many maildirs and I was thinking
> > Gnus would read it as maildirs, instead it started
> > creating .nnmaildir directories inside with copies
> > of those emails for its own way of processing.
> 
> Yeah, I don't think there's any way around the creation of the
> .nnmaildir directories, at least not given the way Gnus currently
> functions. They aren't actually copies of the emails -- just vectors of
> headers for each mail -- but obviously if you've got a lot of mail they
> still take up a lot of space.

If they are not copies, they took as much space as
original emails.

That is opposite and contradictory to what Maildir
is supposed to be.

nnmaildir is thus not described well enough in the
Gnus manual, it is bug in itself.

When somebody mentions "Maildir" that means
managing emails in Maildir folders, and not making
indexes or vectors inside of those Maildir
folders, taking up gigabytes of spaces and
basically endangering integrity of files of the
user. 

Thus that behavior of nnmaildir is bug.

One shall explain it very well in Gnus manual that
nnmaildir is not managing Maildir folders but
rather using Maildir folders to make indexes,
vectors, having some kind of news overlay on top
of Maildir folders.

And one shall mention the limit, as it simple does
not work over certain number of Maildirs. I do not
know how many, as I do have many maildirs. It is
unusable for me.

The package in MELPA "maildir" by Nic Ferrier
http://github.com/nicferrier/emacs-maildir shows
that it is trivial to make Maildir reading and I
am using it sometimes.

True Maildir access is simple, not complex.

Jean