Excessive network traffic for pulling a small change

Colin D Bennett colin at gibibit.com
Thu Mar 11 18:37:22 GMT 2010


On Thu, 11 Mar 2010 19:27:58 +0100
Joke de Buhr <joke at seiken.de> wrote:

> bzr+http:// and bzr+https:// are the smart server transports which
> should be more efficient redarding the amount of transfered data.

Right.  But is the non-smart HTTP transport so inefficient that 2 MB+
must be transferred to retrieve a revision containing only a few changed
lines?

I just thought that the Bazaar storage format was pretty efficient in
terms of reading revisions, so that even a dumb file access protocol
like HTTP or SFTP could avoid downloading 1000x the actual changed data.

> Transports with the "bzr+" prefix are the most efficient ones. They
> cause less data to be transfered.

Yes, and there is an effort to enable bzr+ssh access to Savannah
<https://savannah.gnu.org/support/?107077>.  Hopefully they'll get it
enabled.

> If someone is behind a small-band network connection it's a good idea
> to use lightweight checkouts instead of complete branches with full
> history. Only the most recent changes are transfered much like
> subversion does.

I don't see how that would help.  If you have a standalone branch at
revision X and 'pull' one revision, X+1, from the remote parent branch,
it should be the same network traffic as if you had a checkout and did
an 'update' to get that revision.

Regards,
Colin
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