Rebuild the overview for a single newsgroup

[Russ Allbery]

Lars Magne Ingebrigtsen <larsi at gnus.org> writes:

> Anyway, I should probably explain the weird thing I'm trying to do, and
> you can hopefully tell me whether what I'm trying to do is totally
> insane or not.

> I want to rename newsgroups.

Hm.  Yeah, tdx-util -R will get you fairly close, but there's still one
remaining problem.

> 1) I go through all the articles in gmane.editors.emacs.vms, and
>    rename the Newsgroups headers from gmane.editors.emacs.vms to
>    gmane.emacs.vms.  I do the same for the Xrefs headers.

(Don't forget Followup-To if it ever gets set.)

> The overview DAT file looks OK to me, and everything is owned by the
> user news.  The active file looks OK.  But I can't select the new group:

> 200 main.gmane.org InterNetNews NNRP server INN 2.3.2 ready (posting ok).
> group gmane.emacs.vms
> 211 121 1 121 gmane.emacs.vms
> head 1
> 423 Bad article number

> Any ideas what's happening?

Yeah, unfortunately articles are always retrieved by storage API token,
and the storage API token embeds the number of the newsgroup (per
tradspool.map).  tdx-util -R just grabs the storage API token from the
history file and puts it back into the overview.  So when nnrpd goes to
retrieve the message, it thinks it still should be found in the old
newsgroup.

I *think* that you can fix this, though.  As long as the server is
stopped, I believe you can just change tradspool.map so that the new
newsgroup gets the same number as the old newsgroup had.  Then, the next
time nnrpd reads tradspool.map, which it does when it starts, it should
just magically look in the new directory.

Sneaky, but I think it works.  Not something to do while innd is running,
though, and I don't think even throttling it will cut it because innd
stores tradspool.map internally and just rewrites it on disk and won't
notice changes on disk.  But if you change it while innd isn't running, it
should cope when it starts up again.

> (I know I'll have to rebuild the history file to get fetching by
> message-id to work, but I'm hoping that can be done at a later stage...)

The scary part is that if you change tradspool.map, you shouldn't have to
change anything in the history file.

The trick of changing tradspool.map just occurred to me.

-- 
Russ Allbery (rra at stanford.edu)             <http://www.eyrie.org/~eagle/>

    Please send questions to the list rather than mailing me directly.
     <http://www.eyrie.org/~eagle/faqs/questions.html> explains why.