Re: Changing Default News Server

[Jan Vroonhof <vroonhof@math.ethz.ch>]

Lars Balker Rasmussen <gnort@daimi.aau.dk> writes:

> > The brute force solution would be to get the Message-ID's of all read
> > messages and then look them up on the new server.
> 
> Precisely, that's a brute force ad-hoc solution, which would absolutely
> not work if e.g. my local news-server (which has perverse expiration
> times) was involved.
> 

However it works quite well for small groups. For large groups we are
helped by the fact that the newsreading is done by a human (i.e.
slow).
If you a large group say recs.jobs.offered then most of the time
either one of these is true:

1. Only a few messages are 'read' (i.e. those you actually read).
2. Almost all are read and those that are unread are at the end
(i.e. you have used Catchup).

Case 2 is the difficult one:

Then consider say the last 100 messages of the large "read" block and
look them up on the new server. Lookup the unread articles on the new
server. Take the minum of the article numbers found This gives you a
reasonble lower bound for the unread articles.
Then proceed lower bound upwards to lookup which of the remaing
articles you have read.

This at least gives you a reasonble approximation of wat you want.

Wether this is implementable in e-lisp is another matter.

Jan

P.S. How many articles does rec.jobs.offered have on your news server?

-- 
Jan Vroonhof                    http://www.math.ethz.ch/~vroonhof/
Mathematik,                                  vroonhof@math.ethz.ch
HG E16, ETH-Zentrum,                      Tel: +41-1-6325456/25154
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