The patch has a few bug fixes:
1. The total number of jobs were counted wrongly, which made it very difficult to debug (specially big union queries).
2. The job name for a query was incorrect, , which made it very difficult to debug (specially big union queries).
These two are fixed in Driver.java
3. Union plans were very complex and inefficient - since the unions were not getting merged - the simple fix to to merge
them in the SemanticAnalyzer - no need to check anything, union schema should be the same.
4. No special case for ReduceSink followed by Union – the fix is in GenMRRedSink3
Added a bunch of new tests