org.apache.hadoop.mapreduce.lib.db

クラス DBRecordReader<T extends DBWritable>

java.lang.Object

org.apache.hadoop.mapreduce.RecordReader<LongWritable,T>

org.apache.hadoop.mapreduce.lib.db.DBRecordReader<T>

すべての実装されたインタフェース:

Closeable, AutoCloseable

直系の既知のサブクラス:

DataDrivenDBRecordReader, MySQLDBRecordReader, OracleDBRecordReader

@InterfaceAudience.Public
 @InterfaceStability.Evolving
public class DBRecordReader<T extends DBWritable>
extends RecordReader<LongWritable,T>

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

フィールドのサマリー

フィールド

修飾子とタイプ	フィールドと説明
protected PreparedStatement	statement

コンストラクタのサマリー

コンストラクタ

コンストラクタと説明
DBRecordReader(org.apache.hadoop.mapreduce.lib.db.DBInputFormat.DBInputSplit split, Class<T> inputClass, Configuration conf, Connection conn, DBConfiguration dbConfig, String cond, String[] fields, String table)

メソッドのサマリー

修飾子とタイプ	メソッドと説明
void	close() Close the record reader.
T	createValue() 非推奨です。
protected ResultSet	executeQuery(String query)
protected String	getConditions()
protected Connection	getConnection()
LongWritable	getCurrentKey() Get the current key
T	getCurrentValue() Get the current value.
protected DBConfiguration	getDBConf()
protected String[]	getFieldNames()
long	getPos() 非推奨です。
float	getProgress() The current progress of the record reader through its data.
protected String	getSelectQuery() Returns the query for selecting the records, subclasses can override this for custom behaviour.
protected org.apache.hadoop.mapreduce.lib.db.DBInputFormat.DBInputSplit	getSplit()
protected PreparedStatement	getStatement()
protected String	getTableName()
void	initialize(InputSplit split, TaskAttemptContext context) Called once at initialization.
boolean	next(LongWritable key, T value) 非推奨です。 Use nextKeyValue()
boolean	nextKeyValue() Read the next key, value pair.
protected void	setStatement(PreparedStatement stmt)

クラスから継承されたメソッド java.lang.Object

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

フィールドの詳細

statement

protected PreparedStatement statement

コンストラクタの詳細

DBRecordReader

public DBRecordReader(org.apache.hadoop.mapreduce.lib.db.DBInputFormat.DBInputSplit split,
                      Class<T> inputClass,
                      Configuration conf,
                      Connection conn,
                      DBConfiguration dbConfig,
                      String cond,
                      String[] fields,
                      String table)
               throws SQLException

パラメータ:

split - The InputSplit to read data for

例外:

SQLException

メソッドの詳細

executeQuery

protected ResultSet executeQuery(String query)
                          throws SQLException

例外:

SQLException

getSelectQuery

protected String getSelectQuery()

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

close

public void close()
           throws IOException

Close the record reader.

定義:

close インタフェース内 Closeable

定義:

close インタフェース内 AutoCloseable

定義:

close クラス内 RecordReader<LongWritable,T extends DBWritable>

例外:

IOException

initialize

public void initialize(InputSplit split,
                       TaskAttemptContext context)
                throws IOException,
                       InterruptedException

クラスからコピーされた説明: RecordReader

Called once at initialization.

定義:

initialize クラス内 RecordReader<LongWritable,T extends DBWritable>

パラメータ:

split - the split that defines the range of records to read

context - the information about the task

例外:

IOException

InterruptedException

getCurrentKey

public LongWritable getCurrentKey()

Get the current key

定義:

getCurrentKey クラス内 RecordReader<LongWritable,T extends DBWritable>

戻り値:

the current key or null if there is no current key

getCurrentValue

public T getCurrentValue()

Get the current value.

定義:

getCurrentValue クラス内 RecordReader<LongWritable,T extends DBWritable>

戻り値:

the object that was read

createValue

@Deprecated
public T createValue()

非推奨です。

getPos

@Deprecated
public long getPos()
                        throws IOException

非推奨です。

例外:

IOException

next

@Deprecated
public boolean next(LongWritable key,
                                T value)
                         throws IOException

非推奨です。 Use nextKeyValue()

例外:

IOException

getProgress

public float getProgress()
                  throws IOException

The current progress of the record reader through its data.

定義:

getProgress クラス内 RecordReader<LongWritable,T extends DBWritable>

戻り値:

a number between 0.0 and 1.0 that is the fraction of the data read

例外:

IOException

nextKeyValue

public boolean nextKeyValue()
                     throws IOException

Read the next key, value pair.

定義:

nextKeyValue クラス内 RecordReader<LongWritable,T extends DBWritable>

戻り値:

true if a key/value pair was read

例外:

IOException

getSplit

protected org.apache.hadoop.mapreduce.lib.db.DBInputFormat.DBInputSplit getSplit()

getFieldNames

protected String[] getFieldNames()

getTableName

protected String getTableName()

getConditions

protected String getConditions()

getDBConf

protected DBConfiguration getDBConf()

getConnection

protected Connection getConnection()

getStatement

protected PreparedStatement getStatement()

setStatement

protected void setStatement(PreparedStatement stmt)