Am I right in thinking that the CompositeInputFormat is limited to joining 64 files?
I believe this comes about because TupleWritable uses a single long-type instance field in order to maintain a bitset of tuple slots that have been written to - I'm guessing this is for performance reasons, but it also implies that the TupleWritable only has 64-bits to play with when joining. If my assumptions above are true, could replacing this long with a java.util.BitSet be appropiate in terms of making the map-side join package more scalable?
