Re: Gnus: caching message headers?

[Gregory Heytings via Users list for the GNU Emacs text editor <help-gnu-emacs@gnu.org>]

Hi Eric,

Many thanks for your answer.

>> I would like to have, in the *Summary*, a complete list of the emails 
>> contained in a folder when I hit RET on its label.  Each time I do this 
>> however, Gnus asks me how many articles I want to retrieve, and issues 
>> a "UID FETCH 1:N (UID RFC822.SIZE BODYSTRUCTURE BODY.PEEK[HEADER.FIELDS 
>> (...)])" IMAP command, which can take quite some time to complete when 
>> N is large.
>>
>> Is there a way to convince Gnus to cache the result of that command 
>> (without caching all emails), and to issue a command only for the new 
>> UIDs?  Caching the result of that command should not eat too much disk 
>> space.
>
> No, not at the moment. You can avoid the prompt by customizing the value 
> of `gnus-large-newsgroup', but it's still going to retrieve all the 
> headers for the group.
>
> There's currently no way around this, as Gnus only lets you have one 
> active Summary buffer at a time, which means all the old data is dumped 
> every time you switch groups. In the back of my head I have some ideas 
> for removing this restriction, but it will take a long time to get 
> there.
>

I'm clearly not an expert, but would it not be enough to save and retrieve 
the contents of nntp-server-buffer in nnimap-retrieve-headers?  Or are you 
thinking about a more generic solution that would work with all backends?