From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS31976 209.132.180.0/23 X-Spam-Status: No, score=-5.0 required=3.0 tests=AWL,BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,RCVD_IN_DNSWL_HI,RP_MATCHES_RCVD shortcircuit=no autolearn=ham autolearn_force=no version=3.4.0 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by dcvr.yhbt.net (Postfix) with ESMTP id 616681F4F8 for ; Thu, 29 Sep 2016 02:47:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751226AbcI2CrM (ORCPT ); Wed, 28 Sep 2016 22:47:12 -0400 Received: from iramx2.ira.uni-karlsruhe.de ([141.3.10.81]:43046 "EHLO iramx2.ira.uni-karlsruhe.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750719AbcI2CrL (ORCPT ); Wed, 28 Sep 2016 22:47:11 -0400 Received: from x590e2b22.dyn.telefonica.de ([89.14.43.34] helo=localhost.localdomain) by iramx2.ira.uni-karlsruhe.de with esmtpsa port 587 iface 141.3.10.81 id 1bpRNE-0001l5-Cs; Thu, 29 Sep 2016 04:47:01 +0200 From: =?UTF-8?q?SZEDER=20G=C3=A1bor?= To: Junio C Hamano Cc: =?UTF-8?q?SZEDER=20G=C3=A1bor?= , peff@peff.net, torvalds@linux-foundation.org, git@vger.kernel.org Subject: Re: [PATCH 4/4] core.abbrev: raise the default abbreviation to 12 hexdigits Date: Thu, 29 Sep 2016 04:44:00 +0200 Message-Id: <20160929024400.22605-1-szeder@ira.uka.de> X-Mailer: git-send-email 2.10.0.516.gccda3a9 In-Reply-To: <20160928233047.14313-5-gitster@pobox.com> References: <20160928233047.14313-5-gitster@pobox.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-ATIS-AV: ClamAV (iramx2.ira.uni-karlsruhe.de) X-ATIS-Timestamp: iramx2.ira.uni-karlsruhe.de esmtpsa 1475117222. Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org > As Peff said, responding in a thread started by Linus's suggestion > to raise the default abbreviation to 12 hexdigits: > > I actually think "12" might be sane for a long time. That's 48 bits of > sha1, so we'd expect a 50% change of a _single_ collision at 2^24, or 16 s/change/chance/ I know it's quoted, but still. > million. The biggest repository I know about (in number of objects) is > the one holding all of the objects for all of the forks of > torvalds/linux on GitHub. It's at about 15 million objects. > > Which _seems_ close, but remember that's the size where we expect to see > a single collision. They don't become common until much later (I didn't > compute an exact number, but Linus's 16x sounds about right). I know > that the growth of the kernel isn't really linear, but I think the need > to bump to "13" might not just be decades, but possibly a century or > more. > > So 12 seems reasonable, and the only downside for it (or for "13", for > that matter) is a few extra bytes. I dunno, maybe people will really > hate that, but I have a feeling these are mostly cut-and-pasted anyway. I for one raise my hand in protest... "few extra bytes" is not the only downside, and it's not at all about how many characters are copy-and-pasted. In my opinion it's much more important that this change wastes 5 columns worth of valuable screen real estate e.g. for 'git blame' or 'git log --oneline' in projects that don't need it and certainly won't ever need it. Sure, users working on smaller repos are free to reset core.abbrev to its original value. I don't have any numbers, of course, but I suspect that there are many more smaller repos out there that this change will affect disadvantageously, than there are large repos for which it's beneficial. > And this does exactly that. > > Keep the tests working by explicitly asking for the old 7 hexdigits > setting in the fake system-wide configuration file used for tests. > > Signed-off-by: Junio C Hamano