From: Junio C Hamano <gitster@pobox.com>
To: Michael J Gruber <git@drmicha.warpmail.net>
Cc: Marat Radchenko <marat@slonopotamus.org>, git@vger.kernel.org
Subject: Re: What's the difference between `git show branch:file | diff -u - file` vs `git diff branch file`?
Date: Tue, 23 Aug 2011 10:15:36 -0700 [thread overview]
Message-ID: <7vk4a4rqvb.fsf@alter.siamese.dyndns.org> (raw)
In-Reply-To: <4E53C89A.9000604@drmicha.warpmail.net> (Michael J. Gruber's message of "Tue, 23 Aug 2011 17:34:50 +0200")
Michael J Gruber <git@drmicha.warpmail.net> writes:
> Marat Radchenko venit, vidit, dixit 23.08.2011 12:52:
>>> Is that a very large tree or a very slow file system?
>> Tree is large (500k files), file system is irrelevant since all time is spend on CPU.
>>
>>> Do we enumerate all
>>> differing files and only then limit diff output by path??
>>
>> Dunno, that's why I am asking why it is so slow.
>
> Well, we have to read the full tree before diffing.
Not necessarily, especially when pathspec is given like the original post,
i.e. "git diff $tree_ish -- $path". We would need to open tree objects
that lead to the leaf of the $path and a blob, but other objects won't be
needed.
The default diff backend tries to come up with minimal changes by spending
extra cycles, so it is not so surprising if the file compared is large-ish
and/or has very many similar lines in itself (in which case there are many
potential matching line pairs between the preimage and the postimage to be
examined to produce a minimal diff).
next prev parent reply other threads:[~2011-08-23 17:15 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-23 7:25 What's the difference between `git show branch:file | diff -u - file` vs `git diff branch file`? Marat Radchenko
2011-08-23 10:03 ` Michael J Gruber
2011-08-23 10:52 ` Marat Radchenko
2011-08-23 15:20 ` Michael Witten
2011-08-23 15:34 ` Michael J Gruber
2011-08-23 16:45 ` Marat Radchenko
2011-08-23 17:15 ` Junio C Hamano [this message]
2011-08-23 18:21 ` Marat Radchenko
2011-08-23 20:07 ` Michael J Gruber
2011-08-25 16:09 ` Marat Radchenko
2011-08-25 21:10 ` Junio C Hamano
2011-08-26 9:43 ` Marat Radchenko
2011-08-29 7:41 ` Nguyen Thai Ngoc Duy
2011-08-29 14:48 ` Marat Radchenko
2011-08-29 16:09 ` Nguyen Thai Ngoc Duy
2011-08-29 17:18 ` Junio C Hamano
2011-08-29 20:42 ` Junio C Hamano
2011-08-29 20:50 ` Junio C Hamano
2011-08-29 21:09 ` Junio C Hamano
2011-08-29 21:33 ` [PATCH 0/3] Un-pessimize "diff-index $commit -- $pathspec" Junio C Hamano
2011-08-29 21:33 ` [PATCH 1/3] traverse_trees(): allow pruning with pathspec Junio C Hamano
2011-08-30 12:53 ` Nguyen Thai Ngoc Duy
2011-08-30 17:44 ` Junio C Hamano
2011-08-31 1:35 ` Nguyen Thai Ngoc Duy
2011-10-09 15:39 ` Michael Haggerty
2011-10-09 21:35 ` Nguyen Thai Ngoc Duy
2011-10-10 4:42 ` Michael Haggerty
2011-08-29 21:33 ` [PATCH 2/3] unpack-trees: " Junio C Hamano
2011-08-30 13:03 ` Nguyen Thai Ngoc Duy
2011-08-30 17:32 ` Junio C Hamano
2011-08-30 15:24 ` David Michael Barr
2011-08-29 21:33 ` [PATCH 3/3] diff-index: pass pathspec down to unpack-trees machinery Junio C Hamano
2012-01-11 6:31 ` Jonathan Nieder
2012-01-11 8:05 ` Junio C Hamano
2012-01-11 12:33 ` Nguyen Thai Ngoc Duy
2012-01-11 12:47 ` Nguyen Thai Ngoc Duy
2012-01-11 20:40 ` Junio C Hamano
2012-01-12 4:09 ` [PATCH] tree_entry_interesting: make recursive mode default Nguyễn Thái Ngọc Duy
2012-01-12 5:04 ` Junio C Hamano
2012-01-12 5:44 ` Nguyen Thai Ngoc Duy
2012-01-14 9:23 ` [PATCH v2 1/2] Document limited recursion pathspec matching with wildcards Nguyễn Thái Ngọc Duy
2012-01-14 9:23 ` [PATCH v2 2/2] tree_entry_interesting: make recursive mode default Nguyễn Thái Ngọc Duy
2012-01-15 3:12 ` Junio C Hamano
2012-01-15 10:03 ` Nguyen Thai Ngoc Duy
2012-01-16 22:15 ` Junio C Hamano
2012-01-18 8:59 ` Nguyen Thai Ngoc Duy
2012-01-15 2:38 ` [PATCH v2 1/2] Document limited recursion pathspec matching with wildcards Junio C Hamano
2012-01-15 9:48 ` Nguyen Thai Ngoc Duy
2011-08-29 21:56 ` [PATCH 0/3] Un-pessimize "diff-index $commit -- $pathspec" Linus Torvalds
2011-08-29 22:05 ` Junio C Hamano
2011-08-29 22:11 ` Linus Torvalds
2011-08-29 23:42 ` Junio C Hamano
2011-08-30 6:16 ` Marat Radchenko
2011-08-31 0:18 ` Junio C Hamano
2011-08-30 10:04 ` Michael J Gruber
2011-08-30 17:03 ` Junio C Hamano
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