public boolean isIntersects(KeyInterval other) {
      return (minKey == null || other.maxKey == null || minKey.compareTo(other.maxKey) <= 0) &&
          (maxKey == null || other.minKey == null || maxKey.compareTo(other.minKey) >= 0);
    }
The process here reads several (base + some deltas) files each of which is sorted on 
{@link ReaderKey} ascending.  The output of this Reader should a global order across these
files.  The root of this tree is always the next 'file' to read from.
ql/src/java/org/apache/hadoop/hive/ql/io/orc/OrcRawRecordMerger.java