[NNTP] 64-bit article counter extension strawman

[Steve Walker]

Charles Lindsey wrote:

>In <42DBEF3A.7050305 at nntpserver.com> Steve Walker <nntp at nntpserver.com> writes:
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>>Russ Allbery wrote:
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>>>Do we want to allow rolling over?  Rolling over comes with its own set of
>>>bugs, in particular triggering the low > high logic that causes many
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>>I think rolling over is prone to problems and it's not worth it 
>>when there is there is a good clean method of using 64 bit numbers.
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>And I think exactly the opposite. It is ridiculous using huge numbers
>(approaching 64 bits) to identify articles in a group where the maximum
>number of articles actually existing at any one time is unlikely to exceed
>100,000, and probably nowhere near that.
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A few years ago and I would have agreed.  Today, it's not unreasonable 
to have a binary group with 100 million active articles.  If your server 
software assigns unique article numbers you also will use numbers much 
faster as all articles are in a single "master" group.  This server 
design has some very good benefits with the only downside being that you 
will reach the 32 bit limit in about 2 years on a full feed server.

>So we should look at wrap-around solutions (several variants have been
>mentioned). What are the problems? Special meanings for zero, and several
>ways of detecting whether a group is empty. Is that it?
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Clients have to add a lot of logic for detecting the wraparound.  The 
number zero is a reserved article number, but to do simple % math we 
really need it as a valid number. The xover command has to support a 
high < low number request.   In general, it will be prone to errors. 
Wrapping can work, but it would be complex.

Steve.