Binary diffs and largefiles

Matt Mackall mpm at selenic.com
Thu Sep 20 13:12:29 CDT 2012


On Thu, 2012-09-20 at 09:40 -0500, dukeofgaming wrote:
> Hi,
> 
> I've been doing a little research on binary diffing and patching and I was
> wondering if this was something that made sense for largefiles and how
> binaries are stored.
> 
> http://www.daemonology.net/bsdiff/
> http://dev.chromium.org/developers/design-documents/software-updates-courgette

a) Non-largefiles Mercurial already does "binary diffs" internally that
are probably comparable to bsdiff just fine for files up to hundreds of
MBs
b) One big reason -not- to use plain old Mercurial for large files is
because it can't handle creating/applying deltas on files that are near
the size of memory, but bsdiff uses _much more memory_
c) The most interesting largefiles (JARs/zips/images/movies/audio) are
not compressable/diffable anyway

-- 
Mathematics is the supreme nostalgia of our time.




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