org.apache.hadoop.hive.ql.stats.estimator

Interface StatEstimator

public interface StatEstimator

Enables statistics related computation on UDFs

Method Summary

Modifier and Type	Method and Description
Optional<ColStatistics>	estimate(List<ColStatistics> argStats) Computes the output statistics of the actual UDF.

Method Detail

estimate

Optional<ColStatistics> estimate(List<ColStatistics> argStats)

Computes the output statistics of the actual UDF. The estimator should return with a prefereably overestimated ColStatistics object if possible. The actual estimation logic may decide to not give an estimation; it should return with Optional.empty(). Note: at the time of the call there will be ColStatistics for all the arguments; if that is not available - the estimation is skipped.

Parameters:

argStats - the statistics for every argument of the UDF

Returns:

ColStatistics estimate for the actual UDF.