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

All Known Subinterfaces:

GenericUDAFResolver2

All Known Implementing Classes:

AbstractGenericUDAFResolver, GenericUDAFAverage, GenericUDAFBridge, GenericUDAFCollectList, GenericUDAFCollectSet, GenericUDAFComputeStats, GenericUDAFContextNGrams, GenericUDAFCorrelation, GenericUDAFCount, GenericUDAFCovariance, GenericUDAFCovarianceSample, GenericUDAFCumeDist, GenericUDAFDenseRank, GenericUDAFEWAHBitmap, GenericUDAFFirstValue, GenericUDAFHistogramNumeric, GenericUDAFLag, GenericUDAFLastValue, GenericUDAFLead, GenericUDAFLeadLag, GenericUDAFMax, GenericUDAFMin, GenericUDAFnGrams, GenericUDAFNTile, GenericUDAFPercentileApprox, GenericUDAFPercentRank, GenericUDAFRank, GenericUDAFRowNumber, GenericUDAFStd, GenericUDAFStdSample, GenericUDAFSum, GenericUDAFVariance, GenericUDAFVarianceSample

Deprecated. Use GenericUDAFResolver2 instead.

@Deprecated
public interface GenericUDAFResolver

A Generic User-defined aggregation function (GenericUDAF) for the use with Hive. GenericUDAFResolver is used at compile time. We use GenericUDAFResolver to find out the GenericUDAFEvaluator for the parameter types.

Method Summary

GenericUDAFEvaluator

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

Method Detail

getEvaluator

GenericUDAFEvaluator getEvaluator(TypeInfo[] parameters)
                                  throws SemanticException

Deprecated.

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.

Parameters:

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

Throws:

SemanticException