@Override
    // Chooses a representative alias and index to use as the String, the first is used because
    // it is set in the constructor
    public String toString() {
      return "name: " + names.get(0) + " index: " + indexes.get(0);
    }
BucketCol.

An implementation of BucketSortCol which contains known aliases/indexes of equivalent columns
which data is determined to be bucketed on.
ql/src/java/org/apache/hadoop/hive/ql/optimizer/physical/BucketingSortingCtx.java