From mboxrd@z Thu Jan 1 00:00:00 1970 From: "C. Scott Ananian" Subject: Re: RFC: adding xdelta compression to git Date: Tue, 3 May 2005 11:50:59 -0400 (EDT) Message-ID: References: <200505030657.38309.alonz@nolaviz.org> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Cc: Alon Ziv , git@vger.kernel.org X-From: git-owner@vger.kernel.org Tue May 03 17:47:34 2005 Return-path: Received: from vger.kernel.org ([12.107.209.244]) by ciao.gmane.org with esmtp (Exim 4.43) id 1DSzaW-00034g-9I for gcvg-git@gmane.org; Tue, 03 May 2005 17:45:32 +0200 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261768AbVECPvp (ORCPT ); Tue, 3 May 2005 11:51:45 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261796AbVECPvp (ORCPT ); Tue, 3 May 2005 11:51:45 -0400 Received: from sincerity-forever.csail.mit.edu ([128.30.67.31]:6104 "EHLO sincerity-forever.csail.mit.edu") by vger.kernel.org with ESMTP id S261768AbVECPvo (ORCPT ); Tue, 3 May 2005 11:51:44 -0400 Received: from catfish.lcs.mit.edu ([128.30.67.25] helo=cag.csail.mit.edu) by sincerity-forever.csail.mit.edu with esmtp (Exim 3.36 #1 (Debian)) id 1DSzg3-0007sN-00; Tue, 03 May 2005 11:51:15 -0400 To: Linus Torvalds In-Reply-To: Sender: git-owner@vger.kernel.org Precedence: bulk X-Mailing-List: git@vger.kernel.org On Mon, 2 May 2005, Linus Torvalds wrote: >> * Changes the repository format. > > It wouldn't necessarily. You should be able to do this with _zero_ changes > to existing objects what-so-ever. Yes. The 'chunking' code I posted earlier does this, etc. It's kinda odd computing a SHA-1 including the 'blob \0' header, even when your representation doesn't use this type exactly, but it's no big deal. I'm still tinkering with this, btw; I can get modest improvements in 'real' disk space used, but nothing earth-shattering (yet). I'll post the list of things I tried and how well they worked at some point, just to save people the effort of retrying things. I've been working from the 'no knowledge of commit structure needed' perspective; I think Chris Mason has been using the structure of the commit object to guide delta-fication and showing more impressive space savings. --scott HTAUTOMAT Legion of Doom payment PBPRIME insurgent shortwave AVBUSY Nader PBCABOOSE overthrow explosion Ortega STANDEL ECJOB Sigint FBI ( http://cscott.net/ )