Bug#372712: apt: Shouldn't download pdiffs in all cases

[Goswin von Brederlow <brederlo@informatik.uni-tuebingen.de>]

Mike Hommey <mh+reportbug@glandium.org> writes:

> Package: apt
> Version: 0.6.44
> Severity: wishlist
>
>
> When you don't apt-get update for a while, downloading all the pdiffs
> instead of the full file is actually much longer. There should be a limit
> of days without update after which apt would get the full file and not the
> pdiffs.

There is a limit on the number of pdiff files available. With one file
per day that translates 1:1 into days.

I don't get why it should be slower to download the diff files than
the full file unless you are using ftp. With http the index is fetched
(round trip 1) and then all needed diff files (round trip 2). So
downloading should never be slower.

Does the patching take longer than downloading and bunziping the full
file on your system? I would think that even 10 days patching are
faster than bunziping the file but that is just a guess.

> PS: Is there a way to totally disable the pdiff stuff ? With decent
> bandwidth, it actually takes more times than downloading the full file...
> (Or is the goal to reduce the bandwitdh on the server side ?)

The primary goal was to save all that download time every day on the
slow modem/dsl line. Probably nobody was thinking about GBit to the
next mirror and 2 weeks worth of diffs.

Maybe the number of diffs kept is to big. Maybe not. To decide that
one needs more info about your (and lots of other peoples) network
structure and update seeds/traffic and then find a good compromise.

MfG
        Goswin