org.apache.hadoop.hive.ql.udf.generic
Class GenericUDAFStd

java.lang.Object
  org.apache.hadoop.hive.ql.udf.generic.AbstractGenericUDAFResolver
      org.apache.hadoop.hive.ql.udf.generic.GenericUDAFVariance
          org.apache.hadoop.hive.ql.udf.generic.GenericUDAFStd

All Implemented Interfaces:

GenericUDAFResolver, GenericUDAFResolver2

public class GenericUDAFStd
extends GenericUDAFVariance

Compute the standard deviation by extending GenericUDAFVariance and overriding the terminate() method of the evaluator.

Nested Class Summary

static class

GenericUDAFStd.GenericUDAFStdEvaluator Compute the standard deviation by extending GenericUDAFVarianceEvaluator and overriding the terminate() method of the evaluator.

Nested classes/interfaces inherited from class org.apache.hadoop.hive.ql.udf.generic.GenericUDAFVariance

GenericUDAFVariance.GenericUDAFVarianceEvaluator

Constructor Summary

GenericUDAFStd()

Method Summary

GenericUDAFEvaluator

getEvaluator(TypeInfo[] parameters) Get the evaluator for the parameter types.

Methods inherited from class org.apache.hadoop.hive.ql.udf.generic.AbstractGenericUDAFResolver

getEvaluator

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

GenericUDAFStd

public GenericUDAFStd()

Method Detail

getEvaluator

public GenericUDAFEvaluator getEvaluator(TypeInfo[] parameters)
                                  throws SemanticException

Description copied from interface: GenericUDAFResolver

Get the evaluator for the parameter types. The reason that this function returns an object instead of a class is because it is possible that the object needs some configuration (that can be serialized). In that case the class of the object has to implement the Serializable interface. At execution time, we will deserialize the object from the plan and use it to evaluate the aggregations.

If the class of the object does not implement Serializable, then we will create a new instance of the class at execution time.

Specified by:

getEvaluator in interface GenericUDAFResolver

Overrides:

getEvaluator in class GenericUDAFVariance

Parameters:

parameters - The types of the parameters. We need the type information to know which evaluator class to use.

Throws:

SemanticException