[Pan-users] Re: How do I get a header count for all groups?

[Duncan]

Greg Lee <address@hidden> posted
address@hidden, excerpted below, on  Sat, 01 Sep 2007 17:12:52
+0000:

> Since getting headers can be very time-consuming, very _very_
> time-consuming, I think what's needed is an estimate of the number of
> headers available, which does not involve actually fetching the headers.
>  From the behavior of the newsreader I used previously, I'm guessing
> that information is available from the news server.  I realize the
> disparity between the count of articles and the count of article parts
> would a problem ...

I had forgotten about the get header count option... but yes getting 
overviews would seem the only other option.

Another alternative, perhaps easier on slow connections, would be to get 
X amount of headers, and see how far back that takes you.  300 (the 
default IIRC) may be too few to be significant, tho it'd at least tell 
you if the group was totally vacant, but say 1000.  If you get a thousand 
headers from a group and it goes back an hour, you know it's a pretty 
active group.  If you say get a thousand, but it only fetches 3, and the 
earliest one is a year and a half ago, well...

Finally, it doesn't much help from pan, but you can always telnet into 
the server, and get a count manually.  As you said, it's a simple command 
issued to the news server -- altho the return result isn't necessarily 
accurate.  (The RFCs say it cannot be less than the actual number, but it 
can and sometimes is more than the actual number, and how far off it 
is... that's a server, group, and often time dependent variable.)

IIRC it's the "group" command.  It returns several numbers, including a 
status code, and the first and last article number (as in the xref 
header), followed by the server estimate of the number of posts 
available  Article numbers are sequential, so the estimate shouldn't be 
more than last minus first, but if messages have been canceled, or came 
in out of sequence (maybe they are numbered on an incoming server then 
sent to the customer server, and got stuck in between), or if a spam 
filter removes some after numbering, then there may be fewer messages 
than last minus first or the estimate indicates.  As I mentioned, the 
estimate is allowed to be high, but not low, according to the spec.  This 
allows the client to use the estimate for preallocating a memory buffer 
if desired, if it knows it needs X bytes per article overview.  Of 
course, a buffer overrun isn't a good thing, thus the spec saying it can 
be more than the number of actual messages, but not less.  Again, that's 
"IIRC", and "IMNRC", but the idea is right, even if the details may not 
be exactly so.  It doesn't hurt to read up on things tho, and trying a 
telnet session can be quite enlightening, if you've never done so 
before.  It gives you a MUCH better appreciation of what a news client 
actually does for you behind the scenes. =8^)

-- 
Duncan - List replies preferred.   No HTML msgs.
"Every nonfree program has a lord, a master --
and if you use the program, he is your master."  Richard Stallman