org.apache.hadoop.mapred.lib.db

クラス DBInputFormat<T extends DBWritable>

java.lang.Object

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

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

org.apache.hadoop.mapred.lib.db.DBInputFormat<T>

すべての実装されたインタフェース:

Configurable, InputFormat<LongWritable,T>, JobConfigurable

@InterfaceAudience.Public
 @InterfaceStability.Stable
public class DBInputFormat<T extends DBWritable>
extends DBInputFormat<T>
implements InputFormat<LongWritable,T>, JobConfigurable

フィールドのサマリー

クラスから継承されたフィールド org.apache.hadoop.mapreduce.lib.db.DBInputFormat

conditions, connection, dbConf, dbProductName, fieldNames, tableName

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
DBInputFormat()

メソッドのサマリー

修飾子とタイプ	メソッドと説明
void	configure(JobConf job) Initializes a new instance from a JobConf.
RecordReader<LongWritable,T>	getRecordReader(InputSplit split, JobConf job, Reporter reporter) Get the RecordReader for the given InputSplit.
InputSplit[]	getSplits(JobConf job, int chunks) Logically split the set of input files for the job.
static void	setInput(JobConf job, Class<? extends DBWritable> inputClass, String inputQuery, String inputCountQuery) Initializes the map-part of the job with the appropriate input settings.
static void	setInput(JobConf job, Class<? extends DBWritable> inputClass, String tableName, String conditions, String orderBy, String... fieldNames) Initializes the map-part of the job with the appropriate input settings.

クラスから継承されたメソッド org.apache.hadoop.mapreduce.lib.db.DBInputFormat

closeConnection, createConnection, createDBRecordReader, createRecordReader, getConf, getConnection, getCountQuery, getDBConf, getDBProductName, getSplits, setConf, setInput, setInput

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

コンストラクタの詳細

DBInputFormat

public DBInputFormat()

メソッドの詳細

configure

public void configure(JobConf job)

Initializes a new instance from a JobConf.

定義:

configure インタフェース内 JobConfigurable

パラメータ:

job - the configuration

getRecordReader

public RecordReader<LongWritable,T> getRecordReader(InputSplit split,
                                                    JobConf job,
                                                    Reporter reporter)
                                             throws IOException

Get the RecordReader for the given InputSplit.

It is the responsibility of the RecordReader to respect record boundaries while processing the logical split to present a record-oriented view to the individual task.

定義:

getRecordReader インタフェース内 InputFormat<LongWritable,T extends DBWritable>

パラメータ:

split - the InputSplit

job - the job that this split belongs to

戻り値:

a RecordReader

例外:

IOException

getSplits

public InputSplit[] getSplits(JobConf job,
                              int chunks)
                       throws IOException

Logically split the set of input files for the job.

Each InputSplit is then assigned to an individual Mapper for processing.

Note: The split is a logical split of the inputs and the input files are not physically split into chunks. For e.g. a split could be <input-file-path, start, offset> tuple.

定義:

getSplits インタフェース内 InputFormat<LongWritable,T extends DBWritable>

パラメータ:

job - job configuration.

chunks - the desired number of splits, a hint.

戻り値:

an array of InputSplits for the job.

例外:

IOException

setInput

public static void setInput(JobConf job,
                            Class<? extends DBWritable> inputClass,
                            String tableName,
                            String conditions,
                            String orderBy,
                            String... fieldNames)

Initializes the map-part of the job with the appropriate input settings.

パラメータ:

job - The job

inputClass - the class object implementing DBWritable, which is the Java object holding tuple fields.

tableName - The table to read data from

conditions - The condition which to select data with, eg. '(updated > 20070101 AND length > 0)'

orderBy - the fieldNames in the orderBy clause.

fieldNames - The field names in the table

関連項目:

setInput(JobConf, Class, String, String)

setInput

public static void setInput(JobConf job,
                            Class<? extends DBWritable> inputClass,
                            String inputQuery,
                            String inputCountQuery)

Initializes the map-part of the job with the appropriate input settings.

パラメータ:

job - The job

inputClass - the class object implementing DBWritable, which is the Java object holding tuple fields.

inputQuery - the input query to select fields. Example : "SELECT f1, f2, f3 FROM Mytable ORDER BY f1"

inputCountQuery - the input query that returns the number of records in the table. Example : "SELECT COUNT(f1) FROM Mytable"

関連項目:

setInput(JobConf, Class, String, String, String, String...)