org.apache.hadoop.hbase.mapred

Class TableInputFormatBase

java.lang.Object

org.apache.hadoop.hbase.mapred.TableInputFormatBase

All Implemented Interfaces:

org.apache.hadoop.mapred.InputFormat<ImmutableBytesWritable,Result>

Direct Known Subclasses:

TableInputFormat

@InterfaceAudience.Public
public abstract class TableInputFormatBase
extends Object
implements org.apache.hadoop.mapred.InputFormat<ImmutableBytesWritable,Result>

A Base for TableInputFormats. Receives a Table, a byte[] of input columns and optionally a Filter. Subclasses may use other TableRecordReader implementations.

Subclasses MUST ensure initializeTable(Connection, TableName) is called for an instance to function properly. Each of the entry points to this class used by the MapReduce framework, getRecordReader(InputSplit, JobConf, Reporter) and getSplits(JobConf, int), will call initialize(JobConf) as a convenient centralized location to handle retrieving the necessary configuration information. If your subclass overrides either of these methods, either call the parent version or call initialize yourself.

An example of a subclass:

   class ExampleTIF extends TableInputFormatBase {

      @Override
     protected void initialize(JobConf context) throws IOException {
       // We are responsible for the lifecycle of this connection until we hand it over in
       // initializeTable.
       Connection connection =
          ConnectionFactory.createConnection(HBaseConfiguration.create(job));
       TableName tableName = TableName.valueOf("exampleTable");
       // mandatory. once passed here, TableInputFormatBase will handle closing the connection.
       initializeTable(connection, tableName);
       byte[][] inputColumns = new byte [][] { Bytes.toBytes("columnA"),
         Bytes.toBytes("columnB") };
       // mandatory
       setInputColumns(inputColumns);
       // optional, by default we'll get everything for the given columns.
       Filter exampleFilter = new RowFilter(CompareOp.EQUAL, new RegexStringComparator("aa.*"));
       setRowFilter(exampleFilter);
     }
   }
 

Constructor Summary

Constructors

Constructor and Description
TableInputFormatBase()

Method Summary

Modifier and Type	Method and Description
protected void	closeTable() Close the Table and related objects that were initialized via initializeTable(Connection, TableName).
org.apache.hadoop.mapred.RecordReader<ImmutableBytesWritable,Result>	getRecordReader(org.apache.hadoop.mapred.InputSplit split, org.apache.hadoop.mapred.JobConf job, org.apache.hadoop.mapred.Reporter reporter) Builds a TableRecordReader.
org.apache.hadoop.mapred.InputSplit[]	getSplits(org.apache.hadoop.mapred.JobConf job, int numSplits) Calculates the splits that will serve as input for the map tasks.
protected Table	getTable() Allows subclasses to get the Table.
protected void	initialize(org.apache.hadoop.mapred.JobConf job) Handle subclass specific set up.
protected void	initializeTable(Connection connection, TableName tableName) Allows subclasses to initialize the table information.
protected void	setInputColumns(byte[][] inputColumns)
protected void	setRowFilter(Filter rowFilter) Allows subclasses to set the Filter to be used.
protected void	setTableRecordReader(TableRecordReader tableRecordReader) Allows subclasses to set the TableRecordReader.

Methods inherited from class java.lang.Object

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

Constructor Detail

TableInputFormatBase

public TableInputFormatBase()

Method Detail

getRecordReader

public org.apache.hadoop.mapred.RecordReader<ImmutableBytesWritable,Result> getRecordReader(org.apache.hadoop.mapred.InputSplit split,
                                                                                            org.apache.hadoop.mapred.JobConf job,
                                                                                            org.apache.hadoop.mapred.Reporter reporter)
                                                                                     throws IOException

Builds a TableRecordReader. If no TableRecordReader was provided, uses the default.

Specified by:

getRecordReader in interface org.apache.hadoop.mapred.InputFormat<ImmutableBytesWritable,Result>

Throws:

IOException

See Also:

InputFormat.getRecordReader(InputSplit, JobConf, Reporter)

getSplits

public org.apache.hadoop.mapred.InputSplit[] getSplits(org.apache.hadoop.mapred.JobConf job,
                                                       int numSplits)
                                                throws IOException

Calculates the splits that will serve as input for the map tasks.

Splits are created in number equal to the smallest between numSplits and the number of HRegions in the table. If the number of splits is smaller than the number of HRegions then splits are spanned across multiple HRegions and are grouped the most evenly possible. In the case splits are uneven the bigger splits are placed first in the InputSplit array.

Specified by:

getSplits in interface org.apache.hadoop.mapred.InputFormat<ImmutableBytesWritable,Result>

Parameters:

job - the map task JobConf

numSplits - a hint to calculate the number of splits (mapred.map.tasks).

Returns:

the input splits

Throws:

IOException

See Also:

InputFormat.getSplits(org.apache.hadoop.mapred.JobConf, int)

initializeTable

protected void initializeTable(Connection connection,
                               TableName tableName)
                        throws IOException

Allows subclasses to initialize the table information.

Parameters:

connection - The Connection to the HBase cluster. MUST be unmanaged. We will close.

tableName - The TableName of the table to process. n

Throws:

IOException

setInputColumns

protected void setInputColumns(byte[][] inputColumns)

Parameters:

inputColumns - to be passed in Result to the map task.

getTable

protected Table getTable()

Allows subclasses to get the Table.

setTableRecordReader

protected void setTableRecordReader(TableRecordReader tableRecordReader)

Allows subclasses to set the TableRecordReader. n * to provide other TableRecordReader implementations.

setRowFilter

protected void setRowFilter(Filter rowFilter)

Allows subclasses to set the Filter to be used. n

initialize

protected void initialize(org.apache.hadoop.mapred.JobConf job)
                   throws IOException

Handle subclass specific set up. Each of the entry points used by the MapReduce framework, getRecordReader(InputSplit, JobConf, Reporter) and getSplits(JobConf, int), will call initialize(JobConf) as a convenient centralized location to handle retrieving the necessary configuration information and calling initializeTable(Connection, TableName).

Subclasses should implement their initialize call such that it is safe to call multiple times. The current TableInputFormatBase implementation relies on a non-null table reference to decide if an initialize call is needed, but this behavior may change in the future. In particular, it is critical that initializeTable not be called multiple times since this will leak Connection instances.

Throws:

IOException

closeTable

protected void closeTable()
                   throws IOException

Close the Table and related objects that were initialized via initializeTable(Connection, TableName). n

Throws:

IOException