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Hadoop >> mail # dev >> Using git grafts to merge history across project split


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Re: Using git grafts to merge history across project split
This is great. Thanks, Todd. -C

On Wed, Jan 5, 2011 at 12:36 PM, Todd Lipcon <[EMAIL PROTECTED]> wrote:
> I know many people use git, so wanted to share a neat tip I figured out this
> morning that lets you graft the pre-split history into the post-split
> repositories. I'm using git 1.7.1, not sure how new these features are. Here
> are the steps:
>
> 1) Check out the git repos from git.apache.org into git/hadoop-common,
> git/hadoop-mapreduce, and git/hadoop-hdfs
>
> 2) Set up the common repo as an "alternate object store" for mr and hdfs:
>
> $ echo "/path/to/git/hadoop-common/.git/objects" >
> /path/to/git/hadoop-hdfs/.git/objects/info/alternates
> $ echo "/path/to/git/hadoop-common/.git/objects" >
> /path/to/git/hadoop-mapreduce/.git/objects/info/alternates
> This allows you to look at hashes from common from within your MR or HDFS
> repos. Note that if you move the paths later you'll have to update this
> file!
>
> 3) Set up grafts for the beginning of MR/HDFS history to the pre-split
> commit in common:
> echo 546d96754ffee3142bcbbf4563c624c053d0ed0d
> 6c16dc8cf2b28818c852e95302920a278d07ad0c >
> git/hadoop-mapreduce/.git/info/grafts
> echo 6a3ac690e493c7da45bbf2ae2054768c427fd0e1
> 6c16dc8cf2b28818c852e95302920a278d07ad0c
>> git/hadoop-hdfs/.git/info/grafts
>
> Now when you use commands like git log --follow or git blame, it will pick
> up changes from pre-split as if it were one repository.
>
> Hope others find this useful as well!
> -Todd
> --
> Todd Lipcon
> Software Engineer, Cloudera
>