Module datarush.library

Package com.pervasive.datarush.ports.record

Class BalancedDistribution

java.lang.Object

com.pervasive.datarush.ports.record.DataDistribution

com.pervasive.datarush.ports.record.PartialDataDistribution

com.pervasive.datarush.ports.record.PartialStaticDataDistribution

com.pervasive.datarush.ports.record.BalancedDistribution

public final class BalancedDistribution
extends PartialStaticDataDistribution

Used to redistribute the data in a roughly balanced fashion. Data from all partitions is round-robin partitioned to all other partitions.

See Also:

DataDistribution

Field Summary

Fields

Modifier and Type	Field	Description
static BalancedDistribution	INSTANCE	The singleton instance of this class.

Method Summary

Modifier and Type	Method	Description
AliasSet[]	getAliases()	Returns the fields that are referenced by this distribution.
protected PartitioningFunction	getPartitioningFunction()	Subclasses must override this method to provide the partitioning function to be used
BalancedDistribution	remap(FieldRemapping mapping)	Because BalancedDistribution does not reference any key names, it is not sensitive to transformations to the record namespace and thus this method just returns a reference to this, unmodified.
protected boolean	requiresRepartitionFrom(PartialDataDistribution source)	Subclasses must override this method to declare whether a repartition is required given the source distribution.
String	toString()

Methods inherited from class com.pervasive.datarush.ports.record.PartialStaticDataDistribution

supportsLocalRepartition

Methods inherited from class com.pervasive.datarush.ports.record.PartialDataDistribution

getGatherScheme

Methods inherited from class java.lang.Object

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

Field Detail

INSTANCE

public static final BalancedDistribution INSTANCE

The singleton instance of this class.

Method Detail

toString

public String toString()

Specified by:

toString in class DataDistribution

remap

public BalancedDistribution remap(FieldRemapping mapping)

Because BalancedDistribution does not reference any key names, it is not sensitive to transformations to the record namespace and thus this method just returns a reference to this, unmodified.

Specified by:

remap in class DataDistribution

Parameters:

mapping - the field remapping.

Returns:

this distribution, unmodified

requiresRepartitionFrom

protected boolean requiresRepartitionFrom(PartialDataDistribution source)

Description copied from class: PartialStaticDataDistribution

Subclasses must override this method to declare whether a repartition is required given the source distribution. Implementations may err on the side of caution by always returning true but this may have an impact on performance.

Specified by:

requiresRepartitionFrom in class PartialStaticDataDistribution

Parameters:

source - the source distribution

Returns:

true if a repartition is required, false if this data distribution matches what was specified.

getAliases

public AliasSet[] getAliases()

Description copied from class: DataDistribution

Returns the fields that are referenced by this distribution. Note that it is valid for a distribution to reference no fields, in which case it should return an empty array. This method is used by the framework to validate the distribution is consistent with the type of the record.

Specified by:

getAliases in class DataDistribution

Returns:

the fields that are referenced by this distribution

getPartitioningFunction

protected PartitioningFunction getPartitioningFunction()

Description copied from class: PartialStaticDataDistribution

Subclasses must override this method to provide the partitioning function to be used

Specified by:

getPartitioningFunction in class PartialStaticDataDistribution

Returns:

a partition function