On 28/09/11 15:25, Robert Evans wrote:
> It is kind of a long history and I will try to leave out all of the politics involved to make it shorter. For a long time 0.20 has been the stable release of Hadoop. It is supposedly in sustaining releases now, but many new features keep going in because that is what most people use in production and they do not want to wait several years for a new interesting feature. One of the very big features that went in is security. There was a separate branch created for it which is branch-0.20-security. Branch-0.20-security has essentially replaced branch-0.20 as the 0.20 release branch. All features that go into branch-0.20-security or any other release branch are also supposed to go into trunk first, if they are not specific to branch-0.20-security. So in theory everything in any release has also been applied to trunk.
That said. the new MR engine in 0.23 means that changes to the mapreduce
classes can't be backported from trunk to 0.20.x. Changes there should
go into 0.22 and then into 0.20-security