eu.stratosphere.arraymodel.functions

Class JoinFunction

java.lang.Object

eu.stratosphere.api.common.functions.AbstractFunction

eu.stratosphere.arraymodel.functions.AbstractArrayModelFunction

eu.stratosphere.arraymodel.functions.JoinFunction

All Implemented Interfaces:

Function, GenericJoiner<Value[],Value[],Value[]>

public abstract class JoinFunction
extends AbstractArrayModelFunction
implements GenericJoiner<Value[],Value[],Value[]>

The JoinFunction must be extended to provide a matcher implementation which is called by a Match PACT. By definition, a Match PACT has two input sets of key-value pairs. It calls the match implementation once for each two pairs that share the same key and come from different input sets. It resembles an equality join of both inputs on their keys. For details on the Match PACT read the documentation of the PACT programming model.

The JoinFunction extension must be parameterized with the type of the key that is matched on.

For a match implementation, the match() method must be implemented.

Constructor Summary

Constructors

Constructor and Description
JoinFunction()

Method Summary

Methods

Modifier and Type	Method and Description
Method	getUDFMethod()
abstract void	match(Value[] value1, Value[] value2, Collector<Value[]> out) This method must be implemented to provide a user implementation of a matcher.

Methods inherited from class eu.stratosphere.arraymodel.functions.AbstractArrayModelFunction

getDataTypes

Methods inherited from class eu.stratosphere.api.common.functions.AbstractFunction

close, getIterationRuntimeContext, getRuntimeContext, open, setRuntimeContext

Methods inherited from class java.lang.Object

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

Methods inherited from interface eu.stratosphere.api.common.functions.Function

close, getRuntimeContext, open, setRuntimeContext

Constructor Detail

JoinFunction

public JoinFunction()

Method Detail

match

public abstract void match(Value[] value1,
         Value[] value2,
         Collector<Value[]> out)
                    throws Exception

This method must be implemented to provide a user implementation of a matcher. It is called for each two records that share the same key and come from different inputs.

Specified by:

match in interface GenericJoiner<Value[],Value[],Value[]>

Parameters:

value1 - The record that comes from the first input.

value2 - The record that comes from the second input.

out - A collector that collects all output pairs.

Throws:

Exception - Implementations may forward exceptions, which are caught by the runtime. When the runtime catches an exception, it aborts the combine task and lets the fail-over logic decide whether to retry the combiner execution.

getUDFMethod

public Method getUDFMethod()

Specified by:

getUDFMethod in class AbstractArrayModelFunction