gr.uoa.di.madgik.searchlibrary.operatorlibrary.except
Class ExceptOp

java.lang.Object
  gr.uoa.di.madgik.searchlibrary.operatorlibrary.except.ExceptOp

public class ExceptOp
extends Object

Operator class used to perform a set difference on its input and produces an output holding the produced results. The set produced contains all records in the left input whose key is not present in the records of the right input. No duplicate elimination is performed, therefore a caller wishing to obtain standard SQL EXCEPT semantics should perform duplicate elimination as a subsequent step.

Author:

UoA

Constructor Summary

ExceptOp(URI leftLocator, URI rightLocator, long timeout, TimeUnit timeUnit, StatsContainer stats)
Creates a new ExceptOp with configurable timeout

ExceptOp(URI leftLocator, URI rightLocator, StatsContainer stats)
Creates a new ExceptOp with the default timeout

Method Summary

URI	compute(String leftKeyFieldName, String rightKeyFieldName) Performs the join operation

Methods inherited from class java.lang.Object

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

Constructor Detail

ExceptOp

public ExceptOp(URI leftLocator,
                URI rightLocator,
                StatsContainer stats)

Creates a new ExceptOp with the default timeout

Parameters:

leftLocator - The locator of the left input

rightLocator - The locator of the right input

stats - statistics

ExceptOp

public ExceptOp(URI leftLocator,
                URI rightLocator,
                long timeout,
                TimeUnit timeUnit,
                StatsContainer stats)

Creates a new ExceptOp with configurable timeout

Parameters:

leftLocator - The locator of the left input

rightLocator - The locator of the right input

timeout - The timeout which will be used by the two IRecordReaders and the RecordWriter

timeUnit - The unit of the timeout

stats - Statistics

Method Detail

compute

public URI compute(String leftKeyFieldName,
                   String rightKeyFieldName)
            throws Exception

Performs the join operation

Parameters:

type - The type of resource to create

leftKeyFieldName - The name of the Field of the join key originating from the left locator

rightKeyFieldName - The name of the Field of the join key origiating from the right locator

Returns:

The join result

Throws:

Exception - An unrecoverable for the operation error occured