org.apache.hadoop.mapred.lib.aggregate

类 ValueAggregatorCombiner<K1 extends WritableComparable,V1 extends Writable>

java.lang.Object

org.apache.hadoop.mapred.lib.aggregate.ValueAggregatorJobBase<K1,V1>

org.apache.hadoop.mapred.lib.aggregate.ValueAggregatorCombiner<K1,V1>

所有已实现的接口:

Closeable, AutoCloseable, JobConfigurable, Mapper<K1,V1,Text,Text>, Reducer<Text,Text,Text,Text>

public class ValueAggregatorCombiner<K1 extends WritableComparable,V1 extends Writable>
extends ValueAggregatorJobBase<K1,V1>

This class implements the generic combiner of Aggregate.

字段概要

从类继承的字段 org.apache.hadoop.mapred.lib.aggregate.ValueAggregatorJobBase

aggregatorDescriptorList

构造器概要

构造器

构造器和说明
ValueAggregatorCombiner()

方法概要

方法

限定符和类型	方法和说明
void	close() Do nothing.
void	configure(JobConf job) Combiner does not need to configure.
void	map(K1 arg0, V1 arg1, OutputCollector<Text,Text> arg2, Reporter arg3) Do nothing.
void	reduce(Text key, Iterator<Text> values, OutputCollector<Text,Text> output, Reporter reporter) Combines values for a given key.

从类继承的方法 org.apache.hadoop.mapred.lib.aggregate.ValueAggregatorJobBase

logSpec

从类继承的方法 java.lang.Object

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

构造器详细资料

ValueAggregatorCombiner

public ValueAggregatorCombiner()

方法详细资料

configure

public void configure(JobConf job)

Combiner does not need to configure.

指定者:

configure 在接口中 JobConfigurable

覆盖:

configure 在类中 ValueAggregatorJobBase<K1 extends WritableComparable,V1 extends Writable>

参数:

job - the configuration

reduce

public void reduce(Text key,
          Iterator<Text> values,
          OutputCollector<Text,Text> output,
          Reporter reporter)
            throws IOException

Combines values for a given key.

参数:

key - the key is expected to be a Text object, whose prefix indicates the type of aggregation to aggregate the values.

values - the values to combine

output - to collect combined values

reporter - facility to report progress.

抛出:

IOException

close

public void close()
           throws IOException

Do nothing.

指定者:

close 在接口中 Closeable

指定者:

close 在接口中 AutoCloseable

覆盖:

close 在类中 ValueAggregatorJobBase<K1 extends WritableComparable,V1 extends Writable>

抛出:

IOException

map

public void map(K1 arg0,
       V1 arg1,
       OutputCollector<Text,Text> arg2,
       Reporter arg3)
         throws IOException

Do nothing. Should not be called.

参数:

arg0 - the input key.

arg1 - the input value.

arg2 - collects mapped keys and values.

arg3 - facility to report progress.

抛出:

IOException