Zsync for Packages files
Max Bowsher
maxb at f2s.com
Sat Jul 18 13:58:43 BST 2009
James Westby wrote:
> Mackenzie Morgan wrote:
>> On Friday 17 July 2009 1:13:06 pm Max Bowsher wrote:
>>> Lars Wirzenius wrote:
>>>> I have not compared zsync with pdiffs. Ubuntu does not use pdiffs
>>>> because it generates Packages files every hour, and it seems that ruins
>>>> the usability of pdiffs.
>>> That's interesting - I would have thought that it would simply lead to
>>> many small pdiff files being created, but the system overall still
>>> working fine. How is the usability damaged?
>> (Guessing) Unless you update every hour, the pdiff won't work for you because
>> it's against a newer version than what you've got, maybe?
>
> pdiffs still work in this case, as you keep several around, and then you
> can apply each in turn to get from where you are to the current one.
>
> I believe the issue was that applying many pdiffs (either the
> implementation or the idea) ended up being slower than just grabbing
> the new file when the chain grew to more than a few entries long.
Given the relative size of the release-pocket universe Packages, as
compared with the speed of my net connection, this really wouldn't be a
problem for me.
And, for released distroseries, we still run the publisher hourly, but
for the vast majority of hourly periods, there will be no change in the
Packages file - in which case I'd assume a pdiff would not be generated.
Max.
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