[DISCUSS] Supporting Hadoop-1 and experimental features

[Alan Gates]

There is a lot of forward-looking work going on in various branches of 
Hive:  LLAP, the HBase metastore, and the work to drop the CLI.  It 
would be good to have a way to release this code to users so that they 
can experiment with it.  Releasing it will also provide feedback to 
developers.

At the same time there are discussions on whether to keep supporting 
Hadoop-1.  The burden of supporting older, less used functionality such 
as Hadoop-1 is becoming ever harder as many new features are added.

I propose that the best way to deal with this would be to make a 
branch-1.  We could continue to make new feature releases off of this 
branch (1.3, 1.4, etc.).  This branch would not drop old functionality.  
This provides stability and continuity for users and developers.

We could then merge these new features branches (LLAP, HBase metastore, 
CLI drop) into the trunk, as well as turn on by default newer features 
such as the vectorization and ACID.  We could also drop older, less used 
features such as support for Hadoop-1 and MapReduce.  It will be a while 
before we are ready to make stable, production ready releases of this 
code.  But we could start making alpha quality releases soon.  We would 
call these releases 2.x, to stress the non-backward compatible changes 
such as dropping Hadoop-1.  This will give users a chance to play with 
the new code and developers a chance to get feedback.

Thoughts?