org.apache.pig.data

Class BagFactory

java.lang.Object

org.apache.pig.data.BagFactory

Direct Known Subclasses:

DefaultBagFactory

@InterfaceAudience.Public
 @InterfaceStability.Stable
public abstract class BagFactory
extends Object

Factory for constructing different types of bags. This class is abstract so that users can override the bag factory if they desire to provide their own that returns their implementation of a bag. If the property pig.data.bag.factory.name is set to a class name and pig.data.bag.factory.jar is set to a URL pointing to a jar that contains the above named class, then getInstance() will create an instance of the named class using the indicated jar. Otherwise, it will create an instance of DefaultBagFactory.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	BagFactory() Construct a new BagFactory

Method Summary

Modifier and Type	Method and Description
static BagFactory	getInstance() Get a reference to the singleton factory.
abstract DataBag	newDefaultBag() Get a default (unordered, not distinct) data bag.
abstract DataBag	newDefaultBag(List<Tuple> listOfTuples) Get a default (unordered, not distinct) data bag with an existing list of tuples inserted into the bag.
abstract DataBag	newDistinctBag() Get a distinct data bag.
abstract DataBag	newLimitedSortedBag(Comparator<Tuple> comp, long limit) Get a limited sorted data bag.
abstract DataBag	newSortedBag(Comparator<Tuple> comp) Get a sorted data bag.
protected void	registerBag(DataBag b) Deprecated. As of Pig 0.11, bags register with the SpillableMemoryManager themselves. Register a bag with the SpillableMemoryManager. If the bags created by an implementation of BagFactory are managed by the SpillableMemoryManager then this method should be called each time a new bag is created.
static void	resetSelf() Provided for testing purposes only.

Methods inherited from class java.lang.Object

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

Constructor Detail

BagFactory

protected BagFactory()

Construct a new BagFactory

Method Detail

getInstance

public static BagFactory getInstance()

Get a reference to the singleton factory.

Returns:

BagFactory

newDefaultBag

public abstract DataBag newDefaultBag()

Get a default (unordered, not distinct) data bag.

Returns:

default data bag.

newDefaultBag

public abstract DataBag newDefaultBag(List<Tuple> listOfTuples)

Get a default (unordered, not distinct) data bag with an existing list of tuples inserted into the bag.

Parameters:

listOfTuples - list of tuples to be placed in the bag. This list may not be copied, it may be used directly by the created bag.

Returns:

default data bag.

newLimitedSortedBag

public abstract DataBag newLimitedSortedBag(Comparator<Tuple> comp,
                                            long limit)

Get a limited sorted data bag. Limited sorted bags are sorted bags with number of elements no more than limit.

Parameters:

comp - Comparator that controls how the data is sorted. If null, default comparator will be used.

limit - max number of tuples in bag

Returns:

a sorted data bag

newSortedBag

public abstract DataBag newSortedBag(Comparator<Tuple> comp)

Get a sorted data bag. Sorted bags guarantee that when an iterator is opened on the bag the tuples will be returned in sorted order.

Parameters:

comp - Comparator that controls how the data is sorted. If null, default comparator will be used.

Returns:

a sorted data bag

newDistinctBag

public abstract DataBag newDistinctBag()

Get a distinct data bag. Distinct bags guarantee that when an iterator is opened on the bag, no two tuples returned from the iterator will be equal.

Returns:

distinct data bag

registerBag

@Deprecated
protected void registerBag(DataBag b)

Deprecated. As of Pig 0.11, bags register with the SpillableMemoryManager themselves. Register a bag with the SpillableMemoryManager. If the bags created by an implementation of BagFactory are managed by the SpillableMemoryManager then this method should be called each time a new bag is created.

Parameters:

b - bag to be registered.

resetSelf

public static void resetSelf()

Provided for testing purposes only. This function should never be called by anybody but the unit tests.