More on delta packages
I've been looking at delta packages for Debian based systems more tonight.
Early tests seem to point to generating a delta of the data.tar file contained within the archive[1].
I tested the xbase-clients package from Ubuntu 4.10.
Each .deb file is around 1.9M each.
* A bsdiff of the 2 .deb files generates a 1.7M file [2]
* A bsdiff of the 2 data.tar.gz (the actual package) files was about the same
* But bsdiff produced a 78k diff when I gunziped each data.tar.gz
I will now investigate with more packages from my download cache if this is the case with other packages or if this was just a fluke.
[1] .deb files can be extracted with "ar -xfile"
[2] gzip will introduce a cascading effect with every change making any binary update system ineffective if it relies on finding any common sections (e.g. bsdiff, rsync)
Early tests seem to point to generating a delta of the data.tar file contained within the archive[1].
I tested the xbase-clients package from Ubuntu 4.10.
Each .deb file is around 1.9M each.
* A bsdiff of the 2 .deb files generates a 1.7M file [2]
* A bsdiff of the 2 data.tar.gz (the actual package) files was about the same
* But bsdiff produced a 78k diff when I gunziped each data.tar.gz
I will now investigate with more packages from my download cache if this is the case with other packages or if this was just a fluke.
[1] .deb files can be extracted with "ar -x
[2] gzip will introduce a cascading effect with every change making any binary update system ineffective if it relies on finding any common sections (e.g. bsdiff, rsync)
posted by Andrew at 11:04 pm
1 Comments:
You can try deltup and diffball. I think they will produce better results. You definetly need to unpack all before creating delta.
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