Re: [PATCH] git-bundle: Make thin packs

From: Johannes Schindelin <johannes.schindelin@gmx.de>
Date: Mar 8, 2007, 00:56 UTC
Message-ID: <Pine.LNX.4.63.0703080149320.22628@wbgn013.biozentrum.uni-wuerzburg.de>
In-Reply-To: <Pine.LNX.4.64.0703071632140.5963@woody.linux-foundation.org>

Hi,

On Wed, 7 Mar 2007, Linus Torvalds wrote:

> Does anybody actually use shallow clones in real life?

I don't. That's why I work on push/fetch from/via/into shallow repos.

Show 7 quoted lines

> When I did the numbers a long time ago, the shallow clone didn't 
> actually help much, because it meant that there were no deltas. Which 
> meant that you got 1% of the history for 60% of the price of all 
> history, and the shallow thing didn't really seem to make much sense.
> 
> I guess that for something with a really long history, you'd get 0.001% 
> of the history for 10% of the price, and maybe it makes sense then.

You -- being blessed by not having to work with anything closed -- miss an important fact of commercial software development. Most, if not all, projects in a commercial setting contain binary blobs. For example, a DLL, or a PNG, or a Firmware blob. These are updated regularly. And they delta really awfully bad.

Also, for something as OpenOffice or Mozilla, I guess that if you really only want to work on the newest revision, the _initial_ fetch will be way cheaper than a full clone. Of course I have no numbers here, but that is what my gut feeling says.

Naturally, over time, the shallow clone will fetch in more and more objects from the upstream, eventually being almost as large as if having the complete history, but the user's experience is different: the amount of time needed to get that amount of data is much more widely spread.

Ciao, Dscho