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From: Linus Torvalds <torvalds@linux-foundation.org>
To: Junio C Hamano <gitster@pobox.com>
Cc: Johannes Sixt <j6t@kdbg.org>,
	Git Mailing List <git@vger.kernel.org>, Jeff King <peff@peff.net>
Subject: Re: [PATCH 4/4] core.abbrev: raise the default abbreviation to 12 hexdigits
Date: Thu, 29 Sep 2016 12:06:23 -0700	[thread overview]
Message-ID: <CA+55aFx9Utm9yDZceks+5q9c8ydc2QMYshWwJ0G0GHWWLwSsXQ@mail.gmail.com> (raw)
In-Reply-To: <CA+55aFwbCNiF0nDppZ5SuRcZwc9kNvKYzgyd_bR8Ut8XRW_p4Q@mail.gmail.com>

On Thu, Sep 29, 2016 at 11:55 AM, Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> For the kernel, just the *math* right now actually gives 12
> characters. For current git it actually seems to say that 8 is the
> correct number. For small projects, you'll still see 7.

Sorry, the git number is 9, not 8. The reason is that git has roughly
212k objects, and 9 hex digits gets expected collisions at about 256k
objects.

So the logic means that we'll see 7 hex digits for projects with less
than 16k objects, 8 hex digits if there are less than 64k objects, and
9 hex digits for projects like git that currently have fewer than 256k
objects.

But git itself might not be *that* far from going to 10 hex digits
with my patch.

The kernel uses 12 he digits because the collision math says that's
the right thing for a project with between 4M and 16M objects (with
the kernel being at 5M).

So on the whole the patch really does seem to just do the right thing
automatically.

              Linus

  reply	other threads:[~2016-09-29 19:06 UTC|newest]

Thread overview: 111+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-09-26  1:39 Changing the default for "core.abbrev"? Linus Torvalds
2016-09-26  3:46 ` Junio C Hamano
2016-09-26  4:34   ` Jeff King
2016-09-26  4:45     ` Junio C Hamano
2016-09-26 11:57       ` [PATCH 0/10] helping people resolve ambiguous sha1s Jeff King
2016-09-26 11:59         ` [PATCH 01/10] get_sha1: detect buggy calls with multiple disambiguators Jeff King
2016-09-26 16:37           ` Junio C Hamano
2016-09-26 17:21             ` Jeff King
2016-09-26 17:50               ` Junio C Hamano
2016-09-26 11:59         ` [PATCH 02/10] get_sha1: avoid repeating ourselves via ONLY_TO_DIE Jeff King
2016-09-26 11:59         ` [PATCH 03/10] get_sha1: propagate flags to child functions Jeff King
2016-09-26 11:59         ` [PATCH 04/10] get_short_sha1: peel tags when looking for treeish Jeff King
2016-09-26 12:11           ` Jeff King
2016-09-26 16:55           ` Junio C Hamano
2016-09-26 17:23             ` Jeff King
2016-09-26 12:00         ` [PATCH 05/10] get_short_sha1: refactor init of disambiguation code Jeff King
2016-09-26 12:00         ` [PATCH 06/10] get_short_sha1: NUL-terminate hex prefix Jeff King
2016-09-26 17:10           ` Junio C Hamano
2016-09-26 17:25             ` Jeff King
2016-09-26 17:36               ` Junio C Hamano
2016-09-26 12:00         ` [PATCH 07/10] get_short_sha1: mark ambiguity error for translation Jeff King
2016-09-26 12:00         ` [PATCH 08/10] sha1_array: let callbacks interrupt iteration Jeff King
2016-09-26 12:00         ` [PATCH 09/10] for_each_abbrev: drop duplicate objects Jeff King
2016-09-26 12:00         ` [PATCH 10/10] get_short_sha1: list ambiguous objects on error Jeff King
2016-09-26 16:36           ` Linus Torvalds
2016-09-27  5:42             ` Jacob Keller
2016-09-27 12:38             ` Jeff King
2016-09-29 13:01             ` Kyle J. McKay
2016-09-29 13:24               ` Jeff King
2016-09-29 14:36                 ` Kyle J. McKay
2016-09-29 14:55                   ` Jeff King
2016-09-26 17:30           ` Junio C Hamano
2016-09-26 17:34             ` Jeff King
2016-09-26 17:39               ` Junio C Hamano
2016-09-29 11:46           ` Kyle J. McKay
2016-09-29 13:03             ` Jeff King
2016-09-29 17:19               ` Junio C Hamano
2016-09-30  5:51                 ` Jacob Keller
2019-02-04 16:12     ` [RFC/PATCH] core.abbrev doc: document and test the abbreviation length Ævar Arnfjörð Bjarmason
2019-02-04 19:13       ` Junio C Hamano
2019-02-04 20:04       ` Junio C Hamano
2019-02-04 21:36         ` Ævar Arnfjörð Bjarmason
2019-02-04 23:32         ` Jeff King
2019-02-04 23:50           ` Ævar Arnfjörð Bjarmason
2019-02-06 18:29             ` Jeff King
2019-02-06 18:36               ` Ævar Arnfjörð Bjarmason
2016-09-26  6:33   ` Changing the default for "core.abbrev"? Matthieu Moy
2016-09-26 12:09     ` Jeff King
2016-09-29 13:01   ` Kyle J. McKay
2016-09-26  7:13 ` Christian Couder
2016-09-28 23:30 ` [PATCH 0/4] raising core.abbrev default to 12 hexdigits Junio C Hamano
2016-09-28 23:30   ` [PATCH 1/4] config: allow customizing /etc/gitconfig location Junio C Hamano
2016-09-29  9:53     ` Jakub Narębski
2016-09-29 17:20       ` Junio C Hamano
2016-09-29 17:45         ` Matthieu Moy
2016-09-28 23:30   ` [PATCH 2/4] t13xx: do not assume system config is empty Junio C Hamano
2016-09-29  9:01     ` Jeff King
2016-09-29 18:13       ` Junio C Hamano
2016-09-29 18:26         ` Jeff King
2016-09-29 18:57           ` Junio C Hamano
2016-09-29 19:18             ` Jeff King
2016-09-29 19:57               ` Junio C Hamano
2016-09-29 19:06           ` Junio C Hamano
2016-09-29 19:26             ` Jeff King
2016-09-29 21:03               ` Junio C Hamano
2016-09-29 21:08                 ` Jeff King
2016-09-28 23:30   ` [PATCH 3/4] worktree: honor configuration variables Junio C Hamano
2016-09-28 23:30   ` [PATCH 4/4] core.abbrev: raise the default abbreviation to 12 hexdigits Junio C Hamano
2016-09-29  2:44     ` SZEDER Gábor
2016-09-29  5:27       ` Lukas Fleischer
2016-09-29  9:22         ` Jeff King
2016-09-29  9:15       ` Jeff King
2016-09-29 10:03         ` Matthieu Moy
2016-09-29 12:52         ` SZEDER Gábor
2016-09-29  5:58     ` Johannes Sixt
2016-09-29 18:05       ` Junio C Hamano
2016-09-29 18:37         ` Linus Torvalds
2016-09-29 18:55           ` Linus Torvalds
2016-09-29 19:06             ` Linus Torvalds [this message]
2016-09-29 19:42               ` Junio C Hamano
2016-09-30  0:56               ` Mike Hommey
2016-09-30  1:01                 ` Linus Torvalds
2016-09-30 19:41                   ` Ævar Arnfjörð Bjarmason
2016-09-29 19:16             ` Jeff King
2016-09-29 19:40               ` Linus Torvalds
2016-09-29 19:45                 ` Junio C Hamano
2016-09-29 21:53                   ` Linus Torvalds
2016-09-29 23:13                     ` Junio C Hamano
2016-09-29 23:20                       ` Junio C Hamano
2016-09-30  0:20                       ` Linus Torvalds
2016-09-30  0:28                         ` Linus Torvalds
2016-09-30  0:57                           ` Linus Torvalds
2016-09-30  1:18                             ` Linus Torvalds
2016-09-30  3:54                               ` Junio C Hamano
2016-09-30  4:10                                 ` Junio C Hamano
2016-09-30  4:18                                   ` Linus Torvalds
2016-09-30  4:29                                     ` Linus Torvalds
2016-09-30  4:27                                   ` Junio C Hamano
2016-09-30  4:35                                     ` Junio C Hamano
2016-09-30 18:40                                     ` Junio C Hamano
2016-09-30 18:51                                       ` Linus Torvalds
2016-09-30 19:00                                         ` Junio C Hamano
2016-09-30  4:11                                 ` Linus Torvalds
2016-09-30  8:06                               ` Jeff King
2016-09-30 17:54                                 ` Linus Torvalds
2016-09-30 18:05                                   ` Jeff King
2016-09-30 18:21                                   ` Linus Torvalds
2016-09-30 20:01                                     ` Junio C Hamano
2016-09-30 17:56                                 ` Junio C Hamano
2016-09-30  7:47                       ` Jeff King
2016-09-29  9:25     ` Jeff King

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