Re: Huge win, compressing a window of delta runs as a unit

From: Johannes Schindelin <johannes.schindelin@gmx.de>
Date: Aug 17, 2006, 07:56 UTC
Message-ID: <Pine.LNX.4.63.0608170943470.28360@wbgn013.biozentrum.uni-wuerzburg.de>
In-Reply-To: <20060817040719.GC18500@spearce.org>

Hi,

On Thu, 17 Aug 2006, Shawn Pearce wrote:

Show 5 quoted lines

> Jon Smirl <jonsmirl@gmail.com> wrote:
> > 
> > One entry per delta -  845,42,0150
> > Packed deltas - 295,018,474
> > 65% smaller

Impressed.

> Unfortunately I can't think of a way to make this type of pack
> readable by older software.  So this could be creating a pretty
> big change in the pack format, relatively speaking.  :)

Not necessarily: the format could stay the same, where multiple object names point to the same entry.

It should not be a problem, as long as this change is kept local: the same git tools which created this kind of pack have to read it.

However, I see some real problems when a public repository has a pack like this: if the client is older, the server has to do some real work, especially in the case of a fresh clone. It gets even worse with a public HTTP repo.

The obvious short-time solution would be to make this opt-in, and use it only on private repositories.

Then, one could think about how to handle the delta-chains in the pack protocol (it should be easy, since you just have to store one object instead of a few), and make this a "supports" option.

Ciao, Dscho