org.apache.hadoop.hbase.mapreduce

类 GroupingTableMapper

java.lang.Object

org.apache.hadoop.mapreduce.Mapper<ImmutableBytesWritable,Result,KEYOUT,VALUEOUT>

org.apache.hadoop.hbase.mapreduce.TableMapper<ImmutableBytesWritable,Result>

org.apache.hadoop.hbase.mapreduce.GroupingTableMapper

所有已实现的接口:

org.apache.hadoop.conf.Configurable

@InterfaceAudience.Public
public class GroupingTableMapper
extends TableMapper<ImmutableBytesWritable,Result>
implements org.apache.hadoop.conf.Configurable

Extract grouping columns from input record.

嵌套类概要

从类继承的嵌套类/接口 org.apache.hadoop.mapreduce.Mapper

org.apache.hadoop.mapreduce.Mapper.Context

字段概要

字段

限定符和类型	字段和说明
protected byte[][]	columns The grouping columns.
static String	GROUP_COLUMNS JobConf parameter to specify the columns used to produce the key passed to collect from the map phase.

构造器概要

构造器

构造器和说明
GroupingTableMapper()

方法概要

限定符和类型	方法和说明
protected ImmutableBytesWritable	createGroupKey(byte[][] vals) Create a key by concatenating multiple column values.
protected byte[][]	extractKeyValues(Result r) Extract columns values from the current record.
org.apache.hadoop.conf.Configuration	getConf() Returns the current configuration.
static void	initJob(String table, Scan scan, String groupColumns, Class<? extends TableMapper> mapper, org.apache.hadoop.mapreduce.Job job) Use this before submitting a TableMap job.
void	map(ImmutableBytesWritable key, Result value, org.apache.hadoop.mapreduce.Mapper.Context context) Extract the grouping columns from value to construct a new key.
void	setConf(org.apache.hadoop.conf.Configuration configuration) Sets the configuration.

从类继承的方法 org.apache.hadoop.mapreduce.Mapper

cleanup, run, setup

从类继承的方法 java.lang.Object

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

字段详细资料

GROUP_COLUMNS

public static final String GROUP_COLUMNS

JobConf parameter to specify the columns used to produce the key passed to collect from the map phase.

另请参阅:

常量字段值

columns

protected byte[][] columns

The grouping columns.

构造器详细资料

GroupingTableMapper

public GroupingTableMapper()

方法详细资料

initJob

public static void initJob(String table,
                           Scan scan,
                           String groupColumns,
                           Class<? extends TableMapper> mapper,
                           org.apache.hadoop.mapreduce.Job job)
                    throws IOException

Use this before submitting a TableMap job. It will appropriately set up the job.

参数:

table - The table to be processed.

scan - The scan with the columns etc.

groupColumns - A space separated list of columns used to form the key used in collect.

mapper - The mapper class.

job - The current job.

抛出:

IOException - When setting up the job fails.

map

public void map(ImmutableBytesWritable key,
                Result value,
                org.apache.hadoop.mapreduce.Mapper.Context context)
         throws IOException,
                InterruptedException

Extract the grouping columns from value to construct a new key. Pass the new key and value to reduce. If any of the grouping columns are not found in the value, the record is skipped.

覆盖:

map 在类中 org.apache.hadoop.mapreduce.Mapper<ImmutableBytesWritable,Result,ImmutableBytesWritable,Result>

参数:

key - The current key.

value - The current value.

context - The current context.

抛出:

IOException - When writing the record fails.

InterruptedException - When the job is aborted.

extractKeyValues

protected byte[][] extractKeyValues(Result r)

Extract columns values from the current record. This method returns null if any of the columns are not found.

Override this method if you want to deal with nulls differently.

参数:

r - The current values.

返回:

Array of byte values.

createGroupKey

protected ImmutableBytesWritable createGroupKey(byte[][] vals)

Create a key by concatenating multiple column values.

Override this function in order to produce different types of keys.

参数:

vals - The current key/values.

返回:

A key generated by concatenating multiple column values.

getConf

public org.apache.hadoop.conf.Configuration getConf()

Returns the current configuration.

指定者:

getConf 在接口中 org.apache.hadoop.conf.Configurable

返回:

The current configuration.

另请参阅:

Configurable.getConf()

setConf

public void setConf(org.apache.hadoop.conf.Configuration configuration)

Sets the configuration. This is used to set up the grouping details.

指定者:

setConf 在接口中 org.apache.hadoop.conf.Configurable

参数:

configuration - The configuration to set.

另请参阅:

Configurable.setConf( org.apache.hadoop.conf.Configuration)