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Re: Rsyncable GZIP (was Re: Package metadata server)

On Sun, 2002-04-07 at 19:36, Adam Heath wrote:
> 54 days with of Packages(sid/main/i386) gives 900k of xdeltas.

Thanks for the info.  I think that keeping 54 days of diffs (or xdeltas)
is unnecessary -- most of the benefit is accrued by keeping only 20 days
or so.  But I need real stats on frequency of updates to verify this for

> The problem with xdelta tho, is that it requires both old and new version to
> be available on the same side of the link, to do it's magic.

That's true, but I don't see a problem with that.  If I understand
debian correctly, ocassionally a master server scans over all the newly
uploaded packages and produces a new Packages file.  At that time, the
server will have a copy of the old and new Packages file, and can
produce the delta, placing it in a file with name based on the hash of
the old Packages file.  The master server can then delete the oldest
delta file and replace the old Packages file with the new one.  Mirrors
pick up these changes, and then clients with the old Packages file will
be able to download the delta, since they can compute the same hash. 
Let me know if I got something wrong here.


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