org.apache.hadoop.hive.ql.udf.generic
Class GenericUDAFVariance
java.lang.Object
org.apache.hadoop.hive.ql.udf.generic.GenericUDAFVariance
- All Implemented Interfaces:
- GenericUDAFResolver
- Direct Known Subclasses:
- GenericUDAFStd, GenericUDAFStdSample, GenericUDAFVarianceSample
public class GenericUDAFVariance
- extends Object
- implements GenericUDAFResolver
Compute the variance. This class is extended by:
GenericUDAFVarianceSample
GenericUDAFStd
GenericUDAFStdSample
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
GenericUDAFVariance
public GenericUDAFVariance()
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's 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
- Parameters:
parameters
- The types of the parameters. We need the type
information to know which evaluator class to use.
- Throws:
SemanticException
Copyright © 2009 The Apache Software Foundation