Here's an idea that occurred to me, which I think might make a useful feature:
If one is synchronizing a .gz or.bz2 file via rsync, then this is very
inefficient. Why not transparently unpack it before synchronizing?

According to Google, this was discussed previously in 2001, but perhaps it may
be worth bringing this up again? A quick measurement I did shows that
uncompressing the file before transfer gives an improvement of a factor of 10.
[.tar.bz2 files synchronize fairly efficiently over rsync if most of the archive
contents are unaltered. However, if the archive files all contain many small
changes (e.g. a database dump), the synchronzation is little better than scp.]

Yes, I do know that the real solution is not to use rsync to transfer compressed
files in the first place. So this is just a nice idea (to transparently do the
most obvious thing) rather than a suggestion of great importance.

Thanks very much,

Richard