To give some context, the null semantics in Pig follow SQL's. In SQL, null is viral, so any operation with null results in null. The idea is that null means unknown, not empty. So concat('x', unknown) = unknown.
On Nov 2, 2012, at 3:09 PM, Yang wrote:
> looks a more intuitive result should be "something" , right?
> but on my system it gave null