On Fri, Mar 1, 2013 at 5:49 PM, Julian Foad <julianf...@btopenworld.com> wrote: > No, that's not true. I think the article Ben read was inaccurate. The > '--rsyncable' option doesn't reset the compression after a fixed number of > bytes, but rather at every point where a rolling checksum of the last N bytes > leading up to that point has a certain value. It will resynchronize after an > insertion or deletion. The intervals between resets are irregular but > deterministic. > > Here's an old but readable description and proof-of-concept: > <http://svana.org/kleptog/rgzip.html>. > > Here's an announcement of implementation in pigz: > <http://mail.zlib.net/pipermail/pigz-announce_zlib.net/2012-January/000003.html>. > It's described in more detail in a big comment near the beginning of > 'pigz.c' in the source tarball available at <http://zlib.net/pigz/>.
This is the patch that Debian is actually applying to gzip: http://ozlabs.org/~rusty/gzip.rsync.patch This was the article I had read which sadly is misleading: http://beeznest.wordpress.com/2005/02/03/rsyncable-gzip/ Julian is right, the window is rolling and so it works for inserts and deletions.
