@Override
  protected void completeInitializationOp(Object[] os) throws HiveException {
    // setup mapJoinTables and serdes
    super.completeInitializationOp(os);

    if (isTestingNoHashTableLoad) {
      return;
    }

    MapJoinTableContainer mapJoinTableContainer =
        mapJoinTables[posSingleVectorMapJoinSmallTable];

    setUpHashTable();
  }
This override lets us substitute our own fast vectorized hash table loader.
ql/src/java/org/apache/hadoop/hive/ql/exec/vector/mapjoin/VectorMapJoinCommonOperator.java