org.apache.hadoop.mapreduce.lib.db
Class DataDrivenDBRecordReader<T extends DBWritable>

java.lang.Object
  org.apache.hadoop.mapreduce.RecordReader<LongWritable,T>
      org.apache.hadoop.mapreduce.lib.db.DBRecordReader<T>
          org.apache.hadoop.mapreduce.lib.db.DataDrivenDBRecordReader<T>

All Implemented Interfaces:

Closeable

Direct Known Subclasses:

MySQLDataDrivenDBRecordReader, OracleDataDrivenDBRecordReader

@InterfaceAudience.Public
@InterfaceStability.Evolving
public class DataDrivenDBRecordReader<T extends DBWritable>
extends DBRecordReader<T>

A RecordReader that reads records from a SQL table, using data-driven WHERE clause splits. Emits LongWritables containing the record number as key and DBWritables as value.

Field Summary

Fields inherited from class org.apache.hadoop.mapreduce.lib.db.DBRecordReader

statement

Constructor Summary

DataDrivenDBRecordReader(DBInputFormat.DBInputSplit split, Class<T> inputClass, Configuration conf, Connection conn, DBConfiguration dbConfig, String cond, String[] fields, String table, String dbProduct)

Method Summary

protected String

getSelectQuery() Returns the query for selecting the records, subclasses can override this for custom behaviour.

Methods inherited from class org.apache.hadoop.mapreduce.lib.db.DBRecordReader

close, createValue, executeQuery, getConditions, getConnection, getCurrentKey, getCurrentValue, getDBConf, getFieldNames, getPos, getProgress, getSplit, getStatement, getTableName, initialize, next, nextKeyValue, setStatement

Methods inherited from class java.lang.Object

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

Constructor Detail

DataDrivenDBRecordReader

public DataDrivenDBRecordReader(DBInputFormat.DBInputSplit split,
                                Class<T> inputClass,
                                Configuration conf,
                                Connection conn,
                                DBConfiguration dbConfig,
                                String cond,
                                String[] fields,
                                String table,
                                String dbProduct)
                         throws SQLException

Parameters:

split - The InputSplit to read data for

Throws:

SQLException

Method Detail

getSelectQuery

protected String getSelectQuery()

Returns the query for selecting the records, subclasses can override this for custom behaviour.

Overrides:

getSelectQuery in class DBRecordReader<T extends DBWritable>