org.apache.hadoop.hbase.mapred

Class TableMapReduceUtil

java.lang.Object

org.apache.hadoop.hbase.mapred.TableMapReduceUtil

@InterfaceAudience.Public
 @InterfaceStability.Stable
public class TableMapReduceUtil
extends Object

Utility for TableMap and TableReduce

Constructor Summary

Constructors

Constructor and Description
TableMapReduceUtil()

Method Summary

Modifier and Type	Method and Description
static void	addDependencyJars(JobConf job)
static void	initCredentials(JobConf job)
static void	initTableMapJob(String table, String columns, Class<? extends TableMap> mapper, Class<?> outputKeyClass, Class<?> outputValueClass, JobConf job) Use this before submitting a TableMap job.
static void	initTableMapJob(String table, String columns, Class<? extends TableMap> mapper, Class<?> outputKeyClass, Class<?> outputValueClass, JobConf job, boolean addDependencyJars)
static void	initTableMapJob(String table, String columns, Class<? extends TableMap> mapper, Class<?> outputKeyClass, Class<?> outputValueClass, JobConf job, boolean addDependencyJars, Class<? extends InputFormat> inputFormat) Use this before submitting a TableMap job.
static void	initTableReduceJob(String table, Class<? extends TableReduce> reducer, JobConf job) Use this before submitting a TableReduce job.
static void	initTableReduceJob(String table, Class<? extends TableReduce> reducer, JobConf job, Class partitioner) Use this before submitting a TableReduce job.
static void	initTableReduceJob(String table, Class<? extends TableReduce> reducer, JobConf job, Class partitioner, boolean addDependencyJars) Use this before submitting a TableReduce job.
static void	initTableSnapshotMapJob(String snapshotName, String columns, Class<? extends TableMap> mapper, Class<?> outputKeyClass, Class<?> outputValueClass, JobConf job, boolean addDependencyJars, Path tmpRestoreDir) Sets up the job for reading from a table snapshot.
static void	limitNumMapTasks(String table, JobConf job) Ensures that the given number of map tasks for the given job configuration does not exceed the number of regions for the given table.
static void	limitNumReduceTasks(String table, JobConf job) Ensures that the given number of reduce tasks for the given job configuration does not exceed the number of regions for the given table.
static void	setNumMapTasks(String table, JobConf job) Sets the number of map tasks for the given job configuration to the number of regions the given table has.
static void	setNumReduceTasks(String table, JobConf job) Sets the number of reduce tasks for the given job configuration to the number of regions the given table has.
static void	setScannerCaching(JobConf job, int batchSize) Sets the number of rows to return and cache with each scanner iteration.

Methods inherited from class java.lang.Object

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

Constructor Detail

TableMapReduceUtil

public TableMapReduceUtil()

Method Detail

initTableMapJob

public static void initTableMapJob(String table,
                                   String columns,
                                   Class<? extends TableMap> mapper,
                                   Class<?> outputKeyClass,
                                   Class<?> outputValueClass,
                                   JobConf job)

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

Parameters:

table - The table name to read from.

columns - The columns to scan.

mapper - The mapper class to use.

outputKeyClass - The class of the output key.

outputValueClass - The class of the output value.

job - The current job configuration to adjust.

initTableMapJob

public static void initTableMapJob(String table,
                                   String columns,
                                   Class<? extends TableMap> mapper,
                                   Class<?> outputKeyClass,
                                   Class<?> outputValueClass,
                                   JobConf job,
                                   boolean addDependencyJars)

initTableMapJob

public static void initTableMapJob(String table,
                                   String columns,
                                   Class<? extends TableMap> mapper,
                                   Class<?> outputKeyClass,
                                   Class<?> outputValueClass,
                                   JobConf job,
                                   boolean addDependencyJars,
                                   Class<? extends InputFormat> inputFormat)

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

Parameters:

table - The table name to read from.

columns - The columns to scan.

mapper - The mapper class to use.

outputKeyClass - The class of the output key.

outputValueClass - The class of the output value.

job - The current job configuration to adjust.

addDependencyJars - upload HBase jars and jars for any of the configured job classes via the distributed cache (tmpjars).

initTableSnapshotMapJob

public static void initTableSnapshotMapJob(String snapshotName,
                                           String columns,
                                           Class<? extends TableMap> mapper,
                                           Class<?> outputKeyClass,
                                           Class<?> outputValueClass,
                                           JobConf job,
                                           boolean addDependencyJars,
                                           Path tmpRestoreDir)
                                    throws IOException

Sets up the job for reading from a table snapshot. It bypasses hbase servers and read directly from snapshot files.

Parameters:

snapshotName - The name of the snapshot (of a table) to read from.

columns - The columns to scan.

mapper - The mapper class to use.

outputKeyClass - The class of the output key.

outputValueClass - The class of the output value.

job - The current job to adjust. Make sure the passed job is carrying all necessary HBase configuration.

addDependencyJars - upload HBase jars and jars for any of the configured job classes via the distributed cache (tmpjars).

tmpRestoreDir - a temporary directory to copy the snapshot files into. Current user should have write permissions to this directory, and this should not be a subdirectory of rootdir. After the job is finished, restore directory can be deleted.

Throws:

IOException - When setting up the details fails.

See Also:

TableSnapshotInputFormat

initTableReduceJob

public static void initTableReduceJob(String table,
                                      Class<? extends TableReduce> reducer,
                                      JobConf job)
                               throws IOException

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

Parameters:

table - The output table.

reducer - The reducer class to use.

job - The current job configuration to adjust.

Throws:

IOException - When determining the region count fails.

initTableReduceJob

public static void initTableReduceJob(String table,
                                      Class<? extends TableReduce> reducer,
                                      JobConf job,
                                      Class partitioner)
                               throws IOException

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

Parameters:

table - The output table.

reducer - The reducer class to use.

job - The current job configuration to adjust.

partitioner - Partitioner to use. Pass null to use default partitioner.

Throws:

IOException - When determining the region count fails.

initTableReduceJob

public static void initTableReduceJob(String table,
                                      Class<? extends TableReduce> reducer,
                                      JobConf job,
                                      Class partitioner,
                                      boolean addDependencyJars)
                               throws IOException

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

Parameters:

table - The output table.

reducer - The reducer class to use.

job - The current job configuration to adjust.

partitioner - Partitioner to use. Pass null to use default partitioner.

addDependencyJars - upload HBase jars and jars for any of the configured job classes via the distributed cache (tmpjars).

Throws:

IOException - When determining the region count fails.

initCredentials

public static void initCredentials(JobConf job)
                            throws IOException

Throws:

IOException

limitNumReduceTasks

public static void limitNumReduceTasks(String table,
                                       JobConf job)
                                throws IOException

Ensures that the given number of reduce tasks for the given job configuration does not exceed the number of regions for the given table.

Parameters:

table - The table to get the region count for.

job - The current job configuration to adjust.

Throws:

IOException - When retrieving the table details fails.

limitNumMapTasks

public static void limitNumMapTasks(String table,
                                    JobConf job)
                             throws IOException

Ensures that the given number of map tasks for the given job configuration does not exceed the number of regions for the given table.

Parameters:

table - The table to get the region count for.

job - The current job configuration to adjust.

Throws:

IOException - When retrieving the table details fails.

setNumReduceTasks

public static void setNumReduceTasks(String table,
                                     JobConf job)
                              throws IOException

Sets the number of reduce tasks for the given job configuration to the number of regions the given table has.

Parameters:

table - The table to get the region count for.

job - The current job configuration to adjust.

Throws:

IOException - When retrieving the table details fails.

setNumMapTasks

public static void setNumMapTasks(String table,
                                  JobConf job)
                           throws IOException

Sets the number of map tasks for the given job configuration to the number of regions the given table has.

Parameters:

table - The table to get the region count for.

job - The current job configuration to adjust.

Throws:

IOException - When retrieving the table details fails.

setScannerCaching

public static void setScannerCaching(JobConf job,
                                     int batchSize)

Sets the number of rows to return and cache with each scanner iteration. Higher caching values will enable faster mapreduce jobs at the expense of requiring more heap to contain the cached rows.

Parameters:

job - The current job configuration to adjust.

batchSize - The number of rows to return in batch with each scanner iteration.

addDependencyJars

public static void addDependencyJars(JobConf job)
                              throws IOException

Throws:

IOException

See Also:

org.apache.hadoop.hbase.mapreduce.TableMapReduceUtil#addDependencyJars(org.apache.hadoop.mapreduce.Job)