@Override
  public NumDistinctValueEstimator deserialize(byte[] buf) {
    InputStream is = new ByteArrayInputStream(buf);
    try {
      NumDistinctValueEstimator n = FMSketchUtils.deserializeFM(is);
      is.close();
      return n;
    } catch (IOException e) {
      throw new RuntimeException(e);
    }
  }
Resets a distinctValueEstimator object to its original state.
standalone-metastore/metastore-server/src/main/java/org/apache/hadoop/hive/common/ndv/fm/FMSketch.java