private double calcFPP(int keyCount) {
    int n = keyCount;
    double p = 0.05;

    // Calculation below is consistent with BloomFilter.optimalNumOfBits().
    // Also, we are capping the BloomFilter size below 100 MB (800000000/8)
    while ((-n * Math.log(p) / (Math.log(2) * Math.log(2))) > 800000000) {
      p += 0.05;
    }
    return p;
  }
Calculate the proper False Positive Probability so that the BloomFilter won't grow too big
@param keyCount number of keys
@return FPP
ql/src/java/org/apache/hadoop/hive/ql/exec/persistence/HybridHashTableContainer.java