@Override
  public void clear() {
    for (int i = 0; i < hashPartitions.length; i++) {
      HashPartition hp = hashPartitions[i];
      if (hp != null) {
        LOG.info("Going to clear hash partition " + i);
        hp.clear();
      }
    }
    memoryUsed = 0;
  }
Gets the partition Id into which to spill the big table row
@return partition Id
ql/src/java/org/apache/hadoop/hive/ql/exec/persistence/HybridHashTableContainer.java