public static float getRelativeError(long actualCount, long estimatedCount) {
    float err = (1.0f - ((float) estimatedCount / (float) actualCount)) * 100.0f;
    return err;
  }
Return relative error between actual and estimated cardinality
@param actualCount
         - actual count
@param estimatedCount
         - estimated count
@return relative error
standalone-metastore/metastore-server/src/main/java/org/apache/hadoop/hive/common/ndv/hll/HyperLogLogUtils.java