@Explain(displayName = "Bucket Mapjoin Context", explainLevels = { Level.EXTENDED })
  public BucketMapJoinContext getBucketMapjoinContextExplain() {
    return bucketMapjoinContext != null &&
        bucketMapjoinContext.getBucketFileNameMapping() != null ? bucketMapjoinContext : null;
  }
@param aliasToFetchWork
         the aliasToFetchWork to set
ql/src/java/org/apache/hadoop/hive/ql/plan/MapredLocalWork.java