What is the scenario for a commit with 3 or more parents

I was reading over the Specifying Revisions section in the man entry
gitrevisions. I understand having 2 parent commits with a merge.

I was trying to understand the HEAD^2 style syntax and wondering where
HEAD^3 would be used. From the example diagram, this would be Commit B
but I'm unclear how this would ever happen. Is this some kind of
multi-way merge?

Does git log show the parents in their ordinal order in the "Merge:" line?

Bradley Wagner [off-list ref] wrote:

I was reading over the Specifying Revisions section in the man entry
gitrevisions. I understand having 2 parent commits with a merge.

I was trying to understand the HEAD^2 style syntax and wondering where
HEAD^3 would be used. From the example diagram, this would be Commit B
but I'm unclear how this would ever happen. Is this some kind of
multi-way merge?

Yes.  Its called an octopus merge.  It happpens sometimes when
merging 2 or more otherwise fairly isolated changes in a single
shot.  E.g. `git merge feature-a feature-b thing-c`.
 

Does git log show the parents in their ordinal order in the "Merge:" line?

Yes.

-- 
Shawn.

Heya,

On Wed, Jul 28, 2010 at 21:19, Shawn O. Pearce [off-list ref] wrote:

Yes.  Its called an octopus merge.  It happpens sometimes when
merging 2 or more otherwise fairly isolated changes in a single
shot.  E.g. `git merge feature-a feature-b thing-c`.

Do we have an explanation anywhere as to when one would use a octopus merge?

-- 
Cheers,

Sverre Rabbelier

On Thu, Jul 29, 2010 at 1:55 PM, Sverre Rabbelier [off-list ref] wrote:

Heya,

On Wed, Jul 28, 2010 at 21:19, Shawn O. Pearce [off-list ref] wrote:

quoted

Yes.  Its called an octopus merge.  It happpens sometimes when
merging 2 or more otherwise fairly isolated changes in a single
shot.  E.g. `git merge feature-a feature-b thing-c`.

Do we have an explanation anywhere as to when one would use a octopus merge?

Another question I had about this: isn't this documentation about
"multi-way merge" inaccurate:
http://book.git-scm.com/5_advanced_branching_and_merging.html.

Sounds like it's not equivalent to merging each branch individually.

--
Cheers,

Sverre Rabbelier

On Jul 29, 2010, at 10:55 AM, Sverre Rabbelier wrote:

Heya,

On Wed, Jul 28, 2010 at 21:19, Shawn O. Pearce [off-list ref]  
wrote:

quoted

Yes.  Its called an octopus merge.  It happpens sometimes when
merging 2 or more otherwise fairly isolated changes in a single
shot.  E.g. `git merge feature-a feature-b thing-c`.

Do we have an explanation anywhere as to when one would use a  
octopus merge?

How about if you had two (or more) components with a shared protocol,  
and you updated each to speak a new (and incompatible) protocol.  The  
changes to each component might be done in separate topic branches,  
but you'd want to merge them all at once.

$ git checkout master
$ git merge client-v2 server-v2

Josh

Heya,

On Thu, Jul 29, 2010 at 13:10, Joshua Juran [off-list ref] wrote:

How about if you had two (or more) components with a shared protocol, and
you updated each to speak a new (and incompatible) protocol.  The changes to
each component might be done in separate topic branches, but you'd want to
merge them all at once.

$ git checkout master
$ git merge client-v2 server-v2

Very nice example, but do we have it _documented_ anywhere? If not, it
would be great if you could add that somewhere :)

-- 
Cheers,

Sverre Rabbelier