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From: Jakub Narebski <jnareb@gmail•com>
To: git@vger•kernel.org
Subject: Re: FFmpeg considering GIT
Date: Thu, 03 May 2007 01:48:26 +0200	[thread overview]
Message-ID: <f1b806$nc7$1@sea.gmane.org> (raw)
In-Reply-To: loom.20070502T111026-882@post.gmane.org

Panagiotis Issaris wrote:

> Some of the people of the FFmpeg project are looking at both GIT and Mercurial
> as possible replacements for the current Subversion repository. They have some
> questions regarding the possibility of doing certain things, which I prefer not
> to answer as I am not sure my answer would be correct :) Which is why I am
> posting here...
> 
> The questions are stated in this e-mail [1]. One of the things that are being
> discussed is the following action on a publicly mirrored repository:
> git branch -m master dead_end
> git branch -m last_good master
> 
> I'd think this would fail as people could have pulled from the repository while
> the "dead_end" commit was already available, right?
> 
> There are some other things the FFmpeg maintainer mentions, namely:
> * He wants to be able to revert a commit in some way without "wiping" history.
> That is without committing a patch which reverses the broken commit, as this
> would pollute "git blame". The maintainer sees this as critical feature for
> switching to git as it apparently can be doing using Subversion:
> "in svn we can do this with svn cp from a specific
> revission git and mercurial lack proper copy support"

About removing a commit: assume that you have the following history

  A---B---C---D---E          <---  branch

Now you have noticed that commit C is wrong, and it should not be there.
One solution, which is used usually if the history was published, is to
revert a commit, resulting in the following history:

  A---B---C---D---E---C^-1   <--- branch

(which is what git-revert does).

Now if you didn't publish this history, or you don't care that you are
rewriting history, it is fairly easy to remove commit C (for example
using "git rebase --onto B D E" command), resulting in the following
history:

  A---B---C---D---E
       \
        \
         \----D'--E'          <--- branch

(which after pruning would result in A---B---D'--E' history).

The problem exists _only_ if somebody based his/her work on commit
C or its descendant, i.e. original D, E commits. He/she would have
to rebase his/her work on top of _changed_ (moved) commits D' and E'.

-- 
Jakub Narebski
Warsaw, Poland
ShadeHawk on #git

  reply	other threads:[~2007-05-02 23:48 UTC|newest]

Thread overview: 69+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-05-02  9:29 FFmpeg considering GIT Panagiotis Issaris
2007-05-02 23:48 ` Jakub Narebski [this message]
2007-05-03  1:03   ` Petr Baudis
2007-05-04  0:42     ` Jakub Narebski
2007-05-04  7:21       ` [RFC?] Telling git about more complex relationships between commits (Was: Re: FFmpeg considering GIT) Johan Herland
2007-05-04  9:36         ` Alex Riesen
2007-05-04 11:39           ` Andy Parkins
2007-05-04 12:06             ` Andrew Ruder
2007-05-04 12:30             ` Johan Herland
2007-05-04 11:53           ` Johan Herland
2007-05-04 22:11             ` Alex Riesen
2007-05-05 12:49               ` Johan Herland
2007-05-05 18:03                 ` Alex Riesen
2007-05-05 16:13               ` Johan Herland
2007-05-04 11:10         ` Petr Baudis
2007-05-04 12:22           ` Johan Herland
2007-05-03  1:48 ` FFmpeg considering GIT Martin Langhoff
2007-05-03 18:00 ` Uwe Kleine-König
2007-05-03 20:00   ` Petr Baudis
2007-05-03 20:05     ` david
2007-05-03 20:13       ` Petr Baudis
2007-05-04 13:46     ` Michael Niedermayer
2007-05-04 15:53       ` Andy Parkins
2007-05-04 16:09         ` Johannes Sixt
2007-05-04 17:23           ` Florian Weimer
2007-05-04 16:40       ` Nicolas Pitre
2007-05-04 18:17       ` Carl Worth
2007-05-04 18:25         ` Johan Herland
2007-05-04 20:24         ` Michael Niedermayer
2007-05-05  4:15           ` Linus Torvalds
2007-05-05 13:35         ` Karl Hasselström
2007-05-05 17:26           ` Linus Torvalds
2007-05-05 22:18             ` Linus Torvalds
2007-05-05 22:30               ` Linus Torvalds
2007-05-06  7:49                 ` Junio C Hamano
2007-05-07 12:13                 ` Paul Mackerras
2007-05-07 12:30                   ` Karl Hasselström
2007-05-07 12:50                   ` Johan Herland
2007-05-07 12:56                   ` Alex Riesen
2007-05-08  6:30                     ` Marco Costalba
2007-05-09  4:28                       ` Paul Mackerras
2007-05-09  6:38                         ` Marco Costalba
2007-05-09 18:17                           ` Robin Rosenberg
2007-05-09 18:28                           ` Jan Hudec
2007-05-09 21:09                             ` Fredrik Kuivinen
2007-05-09 21:36                               ` Jan Hudec
2007-05-10 11:20                                 ` Marco Costalba
2007-05-10 16:52                                   ` Jan Hudec
2007-05-07 17:52                   ` Jan Hudec
2007-05-07 22:10                     ` Gábor Farkas
2007-05-07 23:21                       ` Randal L. Schwartz
     [not found]                       ` <fcaeb9bf0705080707x7ad28afelf98ecd93276042d1@mail.gmail.com>
2007-05-08 15:53                         ` Gábor Farkas
2007-05-07 19:10                   ` Junio C Hamano
2007-05-08  2:03                   ` Shawn O. Pearce
2007-05-08  7:26                   ` Jeff King
2007-05-06  7:56             ` Karl Hasselström
2007-05-06 10:19             ` Karl Hasselström
2007-05-06 16:38               ` Linus Torvalds
2007-05-06  8:15           ` Marco Costalba
2007-05-06 11:14             ` Karl Hasselström
2007-05-06 12:19               ` Marco Costalba
2007-05-06 12:33                 ` Karl Hasselström
2007-05-06 12:33                 ` Marco Costalba
2007-05-06 12:59                   ` Karl Hasselström
2007-05-06 13:03                     ` Karl Hasselström
2007-05-09 22:30                     ` Pavel Roskin
  -- strict thread matches above, loose matches on Subject: below --
2007-05-08  3:39 Brett Schwarz
2007-05-08  4:06 ` Paul Mackerras
2007-05-08  4:19   ` Shawn O. Pearce

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