private static void replaceAlias(String[] origin, String[] cloned,
        String alias, String newAlias) {
      if (origin == null || cloned == null || origin.length != cloned.length) {
        return;
      }
      for (int i = 0; i < origin.length; i++) {
        if (origin[i].equals(alias)) {
          cloned[i] = newAlias;
        }
      }
    }
Set alias in the cloned join tree
ql/src/java/org/apache/hadoop/hive/ql/optimizer/SkewJoinOptimizer.java