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

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

All Implemented Interfaces:

GenericUDAFResolver, GenericUDAFResolver2

Direct Known Subclasses:

GenericUDAFLag, GenericUDAFLead

public abstract class GenericUDAFLeadLag
extends AbstractGenericUDAFResolver

abstract class for Lead & lag UDAFs GenericUDAFLeadLag.

Nested Class Summary

static class

GenericUDAFLeadLag.GenericUDAFLeadLagEvaluator

Constructor Summary

GenericUDAFLeadLag()

Method Summary

GenericUDAFEvaluator

getEvaluator(GenericUDAFParameterInfo 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

GenericUDAFLeadLag

public GenericUDAFLeadLag()

Method Detail

getEvaluator

public GenericUDAFEvaluator getEvaluator(GenericUDAFParameterInfo parameters)
                                  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:

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

Throws:

SemanticException