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

Class GenericUDAFApproximateDistinct

java.lang.Object

org.apache.hadoop.hive.ql.udf.generic.AbstractGenericUDAFResolver

org.apache.hadoop.hive.ql.udf.generic.GenericUDAFApproximateDistinct

All Implemented Interfaces:

GenericUDAFResolver, GenericUDAFResolver2

public class GenericUDAFApproximateDistinct
extends AbstractGenericUDAFResolver

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	GenericUDAFApproximateDistinct.CountApproximateDistinctEvaluator
static class	GenericUDAFApproximateDistinct.HyperLogLogEvaluator

Constructor Summary

Constructors

Constructor and Description
GenericUDAFApproximateDistinct()

Method Summary

Modifier and Type	Method and Description
GenericUDAFEvaluator	getEvaluator(GenericUDAFParameterInfo info) Get the evaluator for the parameter types.
GenericUDAFEvaluator	getEvaluator(TypeInfo[] parameters) Get the evaluator for the parameter types.

Methods inherited from class java.lang.Object

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

Constructor Detail

GenericUDAFApproximateDistinct

public GenericUDAFApproximateDistinct()

Method Detail

getEvaluator

public GenericUDAFEvaluator getEvaluator(GenericUDAFParameterInfo info)
                                  throws SemanticException

Description copied from interface: GenericUDAFResolver2

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 GenericUDAFResolver2

Overrides:

getEvaluator in class AbstractGenericUDAFResolver

Parameters:

info - The parameter information that is applicable to the UDAF being invoked.

Throws:

SemanticException

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 AbstractGenericUDAFResolver

Parameters:

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

Throws:

SemanticException