Re: Why am I getting duplicate messages on RSS groups?

[Tim Landscheidt <tim@tim-landscheidt.de>]

Nasser Alkmim <nasser.alkmim@gmail.com> wrote:

> Not sure how to debug this situation, but some RSS feeds that I have in groups end up with duplicate messages.

> I use this "five filters full-text RSS" to extract the full text from some RSS feeds, and it has a limit of 3 items per feed and 12-hours refresh rate.
> Maybe after this 12-hours, the messages are obtained again.

> The duplicate messages have different "Message-ID", but same subject/date and everything else.

> Any ideas?

I'm not sure the /internal/ dates are actually the same: If
I write the data for such duplicate entries to disk (*1):

| (dolist (i '(58302 58461 58609 58757 58905 59053))
|   (with-temp-file (format "/tmp/%d.el" i)
|     (pp (cddr (assoc i nnrss-group-data)) (current-buffer))))

and diff them, some entries change from file to file
(pubDate, author, URL, etc.).  For example, pubDate is:

| $ grep -i date /tmp/*.el
| /tmp/58302.el:       (pubDate nil "Thu, 10 Dec 2020 22:01:00 GMT")
| /tmp/58461.el:       (pubDate nil "Thu, 10 Dec 2020 22:01:00 -0400")
| /tmp/58609.el:       (pubDate nil "Thu, 10 Dec 2020 22:01:00 -0400")
| /tmp/58757.el:       (pubDate nil "Thu, 10 Dec 2020 22:01:00 -0400")
| /tmp/58905.el:       (pubDate nil "Thu, 10 Dec 2020 22:01:00 +0000")
| /tmp/59053.el:       (pubDate nil "Thu, 10 Dec 2020 22:01:00 +0100")
| $

But for all six messages, Gnus says:

| Date: Thu, 10 Dec 2020 22:01:00 +0000 (3 years, 18 weeks ago)

Now if I understand nnrss.el correctly, it considers two en-
tries the same if they only differ in fields listed in
nnrss-ignore-article-fields (which is 'slash:comments by de-
fault), so any changes to an RSS feed entry will create a
new Gnus nnrss message.  What appears to be missing is
treating guid as an indicator that an entry has not changed.

Tim

(*1)   There is probably also a way to do this in Emacs
       (Lisp) itself.