Paul Hammant <p...@hammant.org> writes: > Git doesn't store deltas, and uses a DEFLATE algorithm for > storage. Diffs are meaningless on binary files, of course.
I don't know about git but Subversion does quite a good job on some binary files. Take the compressed tarballs of a couple of Subversion tags: $ svn export http://svn.apache.org/repos/asf/subversion/tags/1.9.5 $ svn export http://svn.apache.org/repos/asf/subversion/tags/1.9.4 $ tar cfz foo1.tar.gz 1.9.5 $ tar cfz foo2.tar.gz 1.9.4 $ svnadmin create repo $ svnmucc -mm -U file://`pwd`/repo put foo1.tar.gz f.tgz $ svnmucc -mm -U file://`pwd`/repo put foo2.tar.gz f.tgz How big are the tarballs? $ ls -lh foo* -rw-r--r-- 1 pm pm 15M Aug 4 13:00 foo1.tar.gz -rw-r--r-- 1 pm pm 15M Aug 4 13:00 foo2.tar.gz How big in the repository? $ ls -lh repo/db/revs/0/[12] -r--r--r-- 1 pm pm 15M Aug 4 13:00 repo/db/revs/0/1 -r--r--r-- 1 pm pm 13M Aug 4 13:00 repo/db/revs/0/2 Saving about 2M. But we can do better if we do compression knowing that deltification will be used: $ tar cf foo1.tar 1.9.5 $ tar cf foo2.tar 1.9.4 $ gzip --rsyncable foo1.tar $ gzip --rsyncable foo2.tar The resulting tarballs are little bigger: -rw-r--r-- 1 pm pm 16M Aug 4 13:05 foo1.tar.gz -rw-r--r-- 1 pm pm 16M Aug 4 13:05 foo2.tar.gz but Subversion can do better deltification: -r--r--r-- 1 pm pm 16M Aug 4 13:05 repo/db/revs/0/1 -r--r--r-- 1 pm pm 5.6M Aug 4 13:05 repo/db/revs/0/2 We have stored two 15MB compressed tarballs in a 21MB repository. -- Philip
