org.apache.hadoop.hive.ql.udf.generic
Class GenericUDAFContextNGrams.GenericUDAFContextNGramEvaluator

java.lang.Object
  org.apache.hadoop.hive.ql.udf.generic.GenericUDAFEvaluator
      org.apache.hadoop.hive.ql.udf.generic.GenericUDAFContextNGrams.GenericUDAFContextNGramEvaluator

All Implemented Interfaces:

Closeable

Enclosing class:

GenericUDAFContextNGrams

public static class GenericUDAFContextNGrams.GenericUDAFContextNGramEvaluator
extends GenericUDAFEvaluator

A constant-space heuristic to estimate the top-k contextual n-grams.

Nested Class Summary

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

GenericUDAFEvaluator.AbstractAggregationBuffer, GenericUDAFEvaluator.AggregationBuffer, GenericUDAFEvaluator.AggregationType, GenericUDAFEvaluator.Mode

Constructor Summary

GenericUDAFContextNGrams.GenericUDAFContextNGramEvaluator()

Method Summary

GenericUDAFEvaluator.AggregationBuffer	getNewAggregationBuffer() Get a new aggregation object.
ObjectInspector	init(GenericUDAFEvaluator.Mode m, ObjectInspector[] parameters) Initialize the evaluator.
void	iterate(GenericUDAFEvaluator.AggregationBuffer agg, Object[] parameters) Iterate through original data.
void	merge(GenericUDAFEvaluator.AggregationBuffer agg, Object obj) Merge with partial aggregation result.
void	reset(GenericUDAFEvaluator.AggregationBuffer agg) Reset the aggregation.
Object	terminate(GenericUDAFEvaluator.AggregationBuffer agg) Get final aggregation result.
Object	terminatePartial(GenericUDAFEvaluator.AggregationBuffer agg) Get partial aggregation result.

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

aggregate, close, configure, evaluate, isEstimable

Methods inherited from class java.lang.Object

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

Constructor Detail

GenericUDAFContextNGrams.GenericUDAFContextNGramEvaluator

public GenericUDAFContextNGrams.GenericUDAFContextNGramEvaluator()

Method Detail

init

public ObjectInspector init(GenericUDAFEvaluator.Mode m,
                            ObjectInspector[] parameters)
                     throws HiveException

Description copied from class: GenericUDAFEvaluator

Initialize the evaluator.

Overrides:

init in class GenericUDAFEvaluator

Parameters:

m - The mode of aggregation.

parameters - The ObjectInspector for the parameters: In PARTIAL1 and COMPLETE mode, the parameters are original data; In PARTIAL2 and FINAL mode, the parameters are just partial aggregations (in that case, the array will always have a single element).

Returns:

The ObjectInspector for the return value. In PARTIAL1 and PARTIAL2 mode, the ObjectInspector for the return value of terminatePartial() call; In FINAL and COMPLETE mode, the ObjectInspector for the return value of terminate() call. NOTE: We need ObjectInspector[] (in addition to the TypeInfo[] in GenericUDAFResolver) for 2 reasons: 1. ObjectInspector contains more information than TypeInfo; and GenericUDAFEvaluator.init at execution time. 2. We call GenericUDAFResolver.getEvaluator at compilation time,

Throws:

HiveException

merge

public void merge(GenericUDAFEvaluator.AggregationBuffer agg,
                  Object obj)
           throws HiveException

Description copied from class: GenericUDAFEvaluator

Merge with partial aggregation result. NOTE: null might be passed in case there is no input data.

Specified by:

merge in class GenericUDAFEvaluator

obj - The partial aggregation result.

Throws:

HiveException

terminatePartial

public Object terminatePartial(GenericUDAFEvaluator.AggregationBuffer agg)
                        throws HiveException

Description copied from class: GenericUDAFEvaluator

Get partial aggregation result.

Specified by:

terminatePartial in class GenericUDAFEvaluator

Returns:

partial aggregation result.

Throws:

HiveException

iterate

public void iterate(GenericUDAFEvaluator.AggregationBuffer agg,
                    Object[] parameters)
             throws HiveException

Description copied from class: GenericUDAFEvaluator

Iterate through original data.

Specified by:

iterate in class GenericUDAFEvaluator

parameters - The objects of parameters.

Throws:

HiveException

terminate

public Object terminate(GenericUDAFEvaluator.AggregationBuffer agg)
                 throws HiveException

Description copied from class: GenericUDAFEvaluator

Get final aggregation result.

Specified by:

terminate in class GenericUDAFEvaluator

Returns:

final aggregation result.

Throws:

HiveException

getNewAggregationBuffer

public GenericUDAFEvaluator.AggregationBuffer getNewAggregationBuffer()
                                                               throws HiveException

Description copied from class: GenericUDAFEvaluator

Get a new aggregation object.

Specified by:

getNewAggregationBuffer in class GenericUDAFEvaluator

Throws:

HiveException

reset

public void reset(GenericUDAFEvaluator.AggregationBuffer agg)
           throws HiveException

Description copied from class: GenericUDAFEvaluator

Reset the aggregation. This is useful if we want to reuse the same aggregation.

Specified by:

reset in class GenericUDAFEvaluator

Throws:

HiveException