org.apache.hadoop.mapred.lib.db
Class DBInputFormat.DBRecordReader

java.lang.Object
  extended by org.apache.hadoop.mapreduce.RecordReader<LongWritable,T>
      extended by org.apache.hadoop.mapreduce.lib.db.DBRecordReader<T>
          extended by org.apache.hadoop.mapred.lib.db.DBInputFormat.DBRecordReader
All Implemented Interfaces:
Closeable, RecordReader<LongWritable,T>
Enclosing class:
DBInputFormat<T extends DBWritable>

protected class DBInputFormat.DBRecordReader
extends DBRecordReader<T>
implements RecordReader<LongWritable,T>

A RecordReader that reads records from a SQL table. Emits LongWritables containing the record number as key and DBWritables as value.


Constructor Summary
protected DBInputFormat.DBRecordReader(DBInputFormat.DBInputSplit split, Class<T> inputClass, JobConf job, Connection conn, DBConfiguration dbConfig, String cond, String[] fields, String table)
           
 
Method Summary
 LongWritable createKey()
          Create an object of the appropriate type to be used as a key.
 T createValue()
          Create an object of the appropriate type to be used as a value.
 long getPos()
          Returns the current position in the input.
 boolean next(LongWritable key, T value)
          Reads the next key/value pair from the input for processing.
 
Methods inherited from class org.apache.hadoop.mapreduce.lib.db.DBRecordReader
close, executeQuery, getConditions, getConnection, getCurrentKey, getCurrentValue, getDBConf, getFieldNames, getProgress, getSelectQuery, getSplit, getStatement, getTableName, initialize, nextKeyValue, setStatement
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 
Methods inherited from interface org.apache.hadoop.mapred.RecordReader
close, getProgress
 

Constructor Detail

DBInputFormat.DBRecordReader

protected DBInputFormat.DBRecordReader(DBInputFormat.DBInputSplit split,
                                       Class<T> inputClass,
                                       JobConf job,
                                       Connection conn,
                                       DBConfiguration dbConfig,
                                       String cond,
                                       String[] fields,
                                       String table)
                                throws SQLException
Parameters:
split - The InputSplit to read data for
Throws:
SQLException
Method Detail

createKey

public LongWritable createKey()
Create an object of the appropriate type to be used as a key.

Specified by:
createKey in interface RecordReader<LongWritable,T extends DBWritable>
Returns:
a new key object.

createValue

public T createValue()
Create an object of the appropriate type to be used as a value.

Specified by:
createValue in interface RecordReader<LongWritable,T extends DBWritable>
Overrides:
createValue in class DBRecordReader<T extends DBWritable>
Returns:
a new value object.

getPos

public long getPos()
            throws IOException
Description copied from interface: RecordReader
Returns the current position in the input.

Specified by:
getPos in interface RecordReader<LongWritable,T extends DBWritable>
Overrides:
getPos in class DBRecordReader<T extends DBWritable>
Returns:
the current position in the input.
Throws:
IOException

next

public boolean next(LongWritable key,
                    T value)
             throws IOException
Reads the next key/value pair from the input for processing.

Specified by:
next in interface RecordReader<LongWritable,T extends DBWritable>
Overrides:
next in class DBRecordReader<T extends DBWritable>
Parameters:
key - the key to read data into
value - the value to read data into
Returns:
true iff a key/value was read, false if at EOF
Throws:
IOException


Copyright © 2009 The Apache Software Foundation