org.apache.flink.table.runtime.functions.aggregate.hyperloglog.HyperLogLogPlusPlus

public class HyperLogLogPlusPlus extends Object

The implement of HyperLogLogPlusPlus is inspired from Apache Spark.

Constructor Details
- HyperLogLogPlusPlus
  
  public HyperLogLogPlusPlus(double relativeSD)
Method Details
- getNumWords
  
  public int getNumWords()
- updateByHashcode
  
  public void updateByHashcode(HllBuffer buffer, long hash)
  
  Update the HLL++ buffer.
- merge
  
  public void merge(HllBuffer buffer1, HllBuffer buffer2)
  
  Merge the HLL buffers by iterating through the registers in both buffers and select the maximum number of leading zeros for each register.
- estimateBias
  
  public double estimateBias(double e)
  
  Estimate the bias using the raw estimates with their respective biases from the HLL++ appendix. We currently use KNN interpolation to determine the bias (as suggested in the paper).
- query
  
  public long query(HllBuffer buffer)
  
  Compute the HyperLogLog estimate.
  Variable names in the HLL++ paper match variable names in the code.
- trueRsd
  
  public double trueRsd()
  
  The rsd of HLL++ is always equal to or better than the rsd requested. This method returns the rsd this instance actually guarantees.
  
  Returns:
  
  the actual rsd.

Class HyperLogLogPlusPlus

Constructor Summary