Lawrence Kesteloot wrote:
>
> Erik Huelsmann wrote:
>
>>> Are you being sarcastic or are you implying that subversion can
>>> somehow do diffs between different versions of a .tar.bz2 file?
>>
>>
>> The latter.
>
>
> I'm curious about this: since bzip sees the tar as one long binary
> stream, won't a change in the first input byte throw off the rest of the
> compression? Or does bzip reset itself periodically so as to generate
> reasonable binary diffs?
bzip2 is based on (usually 900kb sized) blocks. A change to the first
byte would only affect that block. If the second, or any following,
900k chunk remained unchanged a binary diff could make use of that. On
the other hand a one byte insertion or deletion would cascade and change
every block. So I don't believe there is any benefit to be had from
from binary diffing of bzipped tarball. Uncompressed tarballs could
work quite well though.
John
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Received on Wed Mar 3 21:46:34 2004