org.apache.accumulo.core.iterators.user

Class SummingCombiner

java.lang.Object

org.apache.accumulo.core.iterators.WrappingIterator

org.apache.accumulo.core.iterators.Combiner

org.apache.accumulo.core.iterators.TypedValueCombiner<Long>

org.apache.accumulo.core.iterators.LongCombiner

org.apache.accumulo.core.iterators.user.SummingCombiner

All Implemented Interfaces:

OptionDescriber, SortedKeyValueIterator<Key,Value>, YieldingKeyValueIterator<Key,Value>

public class SummingCombiner
extends LongCombiner

A Combiner that interprets Values as Longs and returns their sum.

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.accumulo.core.iterators.LongCombiner

LongCombiner.FixedLenEncoder, LongCombiner.StringEncoder, LongCombiner.Type, LongCombiner.VarLenEncoder

Nested classes/interfaces inherited from class org.apache.accumulo.core.iterators.TypedValueCombiner

TypedValueCombiner.Encoder<V>

Nested classes/interfaces inherited from class org.apache.accumulo.core.iterators.Combiner

Combiner.ValueIterator

Nested classes/interfaces inherited from interface org.apache.accumulo.core.iterators.OptionDescriber

OptionDescriber.IteratorOptions

Field Summary

Fields inherited from class org.apache.accumulo.core.iterators.LongCombiner

CLASS_PREFIX, FIXED_LEN_ENCODER, STRING_ENCODER, TYPE, VAR_LEN_ENCODER

Fields inherited from class org.apache.accumulo.core.iterators.TypedValueCombiner

LOSSY

Fields inherited from class org.apache.accumulo.core.iterators.Combiner

ALL_OPTION, COLUMNS_OPTION, REDUCE_ON_FULL_COMPACTION_ONLY_OPTION

Constructor Summary

Constructors

Constructor and Description
SummingCombiner()

Method Summary

Modifier and Type	Method and Description
OptionDescriber.IteratorOptions	describeOptions() Gets an iterator options object that contains information needed to configure this iterator.
Long	typedReduce(Key key, Iterator<Long> iter) Reduces a list of V into a single V.

Methods inherited from class org.apache.accumulo.core.iterators.LongCombiner

init, safeAdd, setEncodingType, setEncodingType, setEncodingType, validateOptions

Methods inherited from class org.apache.accumulo.core.iterators.TypedValueCombiner

deepCopy, reduce, setEncoder, setEncoder, setLossyness, testEncoder, testEncoder

Methods inherited from class org.apache.accumulo.core.iterators.Combiner

getTopKey, getTopValue, hasTop, next, seek, setColumns, setCombineAllColumns, setReduceOnFullCompactionOnly

Methods inherited from class org.apache.accumulo.core.iterators.WrappingIterator

getSource, setSource

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.accumulo.core.iterators.YieldingKeyValueIterator

enableYielding

Constructor Detail

SummingCombiner

public SummingCombiner()

Method Detail

typedReduce

public Long typedReduce(Key key,
                        Iterator<Long> iter)

Description copied from class: TypedValueCombiner

Reduces a list of V into a single V.

Specified by:

typedReduce in class TypedValueCombiner<Long>

Parameters:

key - The most recent version of the Key being reduced.

iter - An iterator over the V for different versions of the key.

Returns:

The combined V.

describeOptions

public OptionDescriber.IteratorOptions describeOptions()

Description copied from interface: OptionDescriber

Gets an iterator options object that contains information needed to configure this iterator. This object will be used by the accumulo shell to prompt the user to input the appropriate information.

Specified by:

describeOptions in interface OptionDescriber

Overrides:

describeOptions in class LongCombiner

Returns:

an iterator options object