From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Shawn O. Pearce" Subject: Re: [REVISED PATCH 2/6] Introduce commit notes Date: Fri, 20 Jul 2007 00:59:09 -0400 Message-ID: <20070720045909.GM32566@spearce.org> References: <7vejj96igx.fsf@assigned-by-dhcp.cox.net> <7vfy3l3rj0.fsf@assigned-by-dhcp.cox.net> <7vodi83fg7.fsf@assigned-by-dhcp.cox.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Linus Torvalds , Johannes Schindelin , Alberto Bertogli , git@vger.kernel.org, Johan Herland To: Junio C Hamano X-From: git-owner@vger.kernel.org Fri Jul 20 06:59:23 2007 Return-path: Envelope-to: gcvg-git@gmane.org Received: from vger.kernel.org ([209.132.176.167]) by lo.gmane.org with esmtp (Exim 4.50) id 1IBkaI-0006ua-Qy for gcvg-git@gmane.org; Fri, 20 Jul 2007 06:59:23 +0200 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750911AbXGTE7U (ORCPT ); Fri, 20 Jul 2007 00:59:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750886AbXGTE7U (ORCPT ); Fri, 20 Jul 2007 00:59:20 -0400 Received: from corvette.plexpod.net ([64.38.20.226]:49405 "EHLO corvette.plexpod.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750863AbXGTE7T (ORCPT ); Fri, 20 Jul 2007 00:59:19 -0400 Received: from [74.70.48.173] (helo=asimov.home.spearce.org) by corvette.plexpod.net with esmtpa (Exim 4.66) (envelope-from ) id 1IBka8-0001EG-2n; Fri, 20 Jul 2007 00:59:12 -0400 Received: by asimov.home.spearce.org (Postfix, from userid 1000) id 660D620FBAE; Fri, 20 Jul 2007 00:59:10 -0400 (EDT) Content-Disposition: inline In-Reply-To: <7vodi83fg7.fsf@assigned-by-dhcp.cox.net> User-Agent: Mutt/1.5.11 X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - corvette.plexpod.net X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - spearce.org Sender: git-owner@vger.kernel.org Precedence: bulk X-Mailing-List: git@vger.kernel.org Archived-At: Junio C Hamano wrote: > I've long time ago concluded that if we care about reliability > (and we do very much), a bisectable tree without breaking > backward compatibility is impossible. I was hoping to find a > "hole" in tree object format so that I can place an extended > section that is invisible to older versions of git, and place a > table that records offsets of each tree entries to help > bisection and/or perhaps a hash table to help look-up, but I do > not think it is possible. ... > But the tree object format > is designed so tight that I do not see there is any place to put > an extension section. I came to the same conclusion the last time I thought about this problem, for all the same reasons you outlined. And came up with pack v4. Because the only way I could see that we could produce a more optimal tree was to just use a different *compression* of the tree, while still keeping its data the same. Nico seemed to agree at the time, because he worked on the prototype with me. :-) Its still hanging around in my fastimport repository. But has not been merged with any recent Git, and it still needs a lot of work. -- Shawn.