public static KllHistogramEstimator getKllHistogramEstimator(byte[] buf) {
    return new KllHistogramEstimator(KllUtils.deserializeKll(buf, 0, buf.length));
  }
This function deserializes the serialized KLL histogram estimator from a byte array.
@param buf to deserialize
@return KLL histogram estimator
standalone-metastore/metastore-server/src/main/java/org/apache/hadoop/hive/common/histogram/KllHistogramEstimatorFactory.java