Class HashJoinIteration

java.lang.Object

org.eclipse.rdf4j.common.iteration.AbstractCloseableIteration<BindingSet>

org.eclipse.rdf4j.common.iteration.LookAheadIteration<BindingSet>

org.eclipse.rdf4j.query.algebra.evaluation.iterator.HashJoinIteration

All Implemented Interfaces:

AutoCloseable, Iterator<BindingSet>, CloseableIteration<BindingSet>

public class HashJoinIteration
extends LookAheadIteration<BindingSet>

Generic hash join implementation suitable for use by Sail implementations.

Author:

MJAHale

Field Summary

Fields

Modifier and Type	Field	Description
protected final String[]	joinAttributes

Fields inherited from interface CloseableIteration

EMPTY_STATEMENT_ITERATION

Constructor Summary

Constructors

Constructor	Description
HashJoinIteration(CloseableIteration<BindingSet> leftIter, Set<String> leftBindingNames, CloseableIteration<BindingSet> rightIter, Set<String> rightBindingNames, boolean leftJoin)	Deprecated, for removal: This API element is subject to removal in a future version.
HashJoinIteration(QueryEvaluationStep left, QueryEvaluationStep right, BindingSet bindings, boolean leftJoin, String[] joinAttributes, QueryEvaluationContext context)

Method Summary

Modifier and Type	Method	Description
protected <E> void	add(Collection<E> col, E value)
protected <E> void	addAll(Collection<E> col, List<E> values)
protected <E> void	closeHashValue(Iterator<E> iter)	Utility methods to clear-up in case not using in-memory hash table.
protected void	disposeCache(Iterator<BindingSet> iter)	Utility methods to clear-up in case not using in-memory cache.
protected void	disposeHashTable(Map<BindingSetHashKey, List<BindingSet>> map)	Utility methods to clear-up in case not using in-memory hash table.
protected BindingSet	getNextElement()	Gets the next element.
protected void	handleClose()	Called by AbstractCloseableIteration.close() when it is called for the first time.
static String[]	hashJoinAttributeNames(Join join)
static String[]	hashJoinAttributeNames(LeftJoin join)
protected Map<BindingSetHashKey, List<BindingSet>>	makeHashTable(int initialSize)	Utility methods to make it easier to inserted custom store dependent maps
protected List<BindingSet>	makeHashValue(int currentMaxListSize)	Utility methods to make it easier to inserted custom store dependent list
protected Collection<BindingSet>	makeIterationCache(CloseableIteration<BindingSet> iter)	Utility methods to make it easier to inserted custom store dependent list
protected <E> E	nextFromCache(Iterator<E> iter)
protected void	putHashTableEntry(Map<BindingSetHashKey, List<BindingSet>> nextHashTable, BindingSetHashKey hashKey, List<BindingSet> hashValue, boolean newEntry)

Methods inherited from class LookAheadIteration

hasNext, next, remove

Methods inherited from class AbstractCloseableIteration

close, isClosed

Methods inherited from class Object

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

Methods inherited from interface CloseableIteration

stream

Methods inherited from interface Iterator

forEachRemaining

Field Details

joinAttributes

protected final String[] joinAttributes

Constructor Details

HashJoinIteration

public HashJoinIteration(QueryEvaluationStep left,
 QueryEvaluationStep right,
 BindingSet bindings,
 boolean leftJoin,
 String[] joinAttributes,
 QueryEvaluationContext context)
                  throws QueryEvaluationException

Throws:

QueryEvaluationException

HashJoinIteration

@Deprecated(since="5.0.0",
            forRemoval=true)
public HashJoinIteration(CloseableIteration<BindingSet> leftIter,
 Set<String> leftBindingNames,
 CloseableIteration<BindingSet> rightIter,
 Set<String> rightBindingNames,
 boolean leftJoin)
                  throws QueryEvaluationException

Deprecated, for removal: This API element is subject to removal in a future version.

Throws:

QueryEvaluationException

Method Details

getNextElement

protected BindingSet getNextElement()
                             throws QueryEvaluationException

Description copied from class: LookAheadIteration

Gets the next element. Subclasses should implement this method so that it returns the next element.

Specified by:

getNextElement in class LookAheadIteration<BindingSet>

Returns:

The next element, or null if no more elements are available.

Throws:

QueryEvaluationException

handleClose

protected void handleClose()
                    throws QueryEvaluationException

Description copied from class: AbstractCloseableIteration

Called by AbstractCloseableIteration.close() when it is called for the first time. This method is only called once on each iteration. By default, this method does nothing.

Specified by:

handleClose in class AbstractCloseableIteration<BindingSet>

Throws:

QueryEvaluationException

putHashTableEntry

protected void putHashTableEntry(Map<BindingSetHashKey, List<BindingSet>> nextHashTable,
 BindingSetHashKey hashKey,
 List<BindingSet> hashValue,
 boolean newEntry)
                          throws QueryEvaluationException

Throws:

QueryEvaluationException

makeIterationCache

protected Collection<BindingSet> makeIterationCache(CloseableIteration<BindingSet> iter)

Utility methods to make it easier to inserted custom store dependent list

Returns:

list

makeHashTable

protected Map<BindingSetHashKey, List<BindingSet>> makeHashTable(int initialSize)

Utility methods to make it easier to inserted custom store dependent maps

Returns:

map

makeHashValue

protected List<BindingSet> makeHashValue(int currentMaxListSize)

Utility methods to make it easier to inserted custom store dependent list

Returns:

list

disposeCache

protected void disposeCache(Iterator<BindingSet> iter)

Utility methods to clear-up in case not using in-memory cache.

disposeHashTable

protected void disposeHashTable(Map<BindingSetHashKey, List<BindingSet>> map)

Utility methods to clear-up in case not using in-memory hash table.

closeHashValue

protected <E> void closeHashValue(Iterator<E> iter)

Utility methods to clear-up in case not using in-memory hash table.

nextFromCache

protected <E> E nextFromCache(Iterator<E> iter)

add

protected <E> void add(Collection<E> col,
 E value)
                throws QueryEvaluationException

Throws:

QueryEvaluationException

addAll

protected <E> void addAll(Collection<E> col,
 List<E> values)
                   throws QueryEvaluationException

Throws:

QueryEvaluationException

hashJoinAttributeNames

public static String[] hashJoinAttributeNames(Join join)

hashJoinAttributeNames

public static String[] hashJoinAttributeNames(LeftJoin join)