Package org.eclipse.rdf4j.query.algebra.evaluation

Interface TripleSource

All Superinterfaces:

AvailableStatementOrder

All Known Subinterfaces:

RDFStarTripleSource

All Known Implementing Classes:

RepositoryTripleSource, SailDatasetTripleSource, SailTripleSource

public interface TripleSource
extends AvailableStatementOrder

A triple source that can be queried for (the existence of) certain triples in certain contexts. This interface defines the methods that are needed by the Sail Query Model to be able to evaluate itself.

Field Summary

Fields

Modifier and Type	Field	Description
static final EmptyIteration<? extends Statement>	EMPTY_ITERATION

Method Summary

Modifier and Type	Method	Description
default Comparator<Value>	getComparator()	Different underlying datastructures may have different ways of ordering statements.
default CloseableIteration<? extends Statement>	getStatements(StatementOrder order, Resource subj, IRI pred, Value obj, Resource... contexts)	Gets all statements that have a specific subject, predicate and/or object.
CloseableIteration<? extends Statement>	getStatements(Resource subj, IRI pred, Value obj, Resource... contexts)	Gets all statements that have a specific subject, predicate and/or object.
default Set<StatementOrder>	getSupportedOrders(Resource subj, IRI pred, Value obj, Resource... contexts)	The underlying store may support some, but not all, statement orders based on the statement pattern.
ValueFactory	getValueFactory()	Gets a ValueFactory object that can be used to create IRI-, blank node- and literal objects.

Field Details

EMPTY_ITERATION

static final EmptyIteration<? extends Statement> EMPTY_ITERATION

Method Details

getStatements

CloseableIteration<? extends Statement> getStatements(Resource subj,
 IRI pred,
 Value obj,
 Resource... contexts)
                                               throws QueryEvaluationException

Gets all statements that have a specific subject, predicate and/or object. All three parameters may be null to indicate wildcards. Optionally a (set of) context(s) may be specified in which case the result will be restricted to statements matching one or more of the specified contexts.

Parameters:

subj - A Resource specifying the subject, or null for a wildcard.

pred - A IRI specifying the predicate, or null for a wildcard.

obj - A Value specifying the object, or null for a wildcard.

contexts - The context(s) to get the statements from. Note that this parameter is a vararg and as such is optional. If no contexts are supplied the method operates on the entire repository.

Returns:

An iterator over the relevant statements.

Throws:

QueryEvaluationException - If the triple source failed to get the statements.

getStatements

@Experimental
default CloseableIteration<? extends Statement> getStatements(StatementOrder order,
 Resource subj,
 IRI pred,
 Value obj,
 Resource... contexts)
                                                       throws QueryEvaluationException

Gets all statements that have a specific subject, predicate and/or object. All three parameters may be null to indicate wildcards. Optionally a (set of) context(s) may be specified in which case the result will be restricted to statements matching one or more of the specified contexts.

Statements are returned in the order specified by the statementOrder parameter. Use getSupportedOrders(Resource, IRI, Value, Resource...) to first retrieve the statement orders supported by this store for this statement pattern.

Note that this method is experimental and may be changed or removed without notice.

Parameters:

order - The order in which the statements should be returned.

subj - A Resource specifying the subject, or null for a wildcard.

pred - A IRI specifying the predicate, or null for a wildcard.

obj - A Value specifying the object, or null for a wildcard.

contexts - The context(s) to get the statements from. Note that this parameter is a vararg and as such is optional. If no contexts are supplied the method operates on the entire repository.

Returns:

An ordered iterator over the relevant statements.

Throws:

QueryEvaluationException - If the triple source failed to get the statements.

getSupportedOrders

@Experimental
default Set<StatementOrder> getSupportedOrders(Resource subj,
 IRI pred,
 Value obj,
 Resource... contexts)

The underlying store may support some, but not all, statement orders based on the statement pattern. This method can be used to determine which orders are supported for a given statement pattern. The supported orders can be used to retrieve statements in a specific order using getStatements(StatementOrder, Resource, IRI, Value, Resource...) .

Note that this method is experimental and may be changed or removed without notice.

Specified by:

getSupportedOrders in interface AvailableStatementOrder

Parameters:

subj - A Resource specifying the subject, or null for a wildcard.

pred - A IRI specifying the predicate, or null for a wildcard.

obj - A Value specifying the object, or null for a wildcard.

contexts - The context(s) to get the data from. Note that this parameter is a vararg and as such is optional. If no contexts are specified the method operates on the entire repository. A null value can be used to match context-less statements.

Returns:

a set of supported statement orders

getComparator

@Experimental
default Comparator<Value> getComparator()

Different underlying datastructures may have different ways of ordering statements. On-disk stores typically use a long to represent a value and only stores the actual value in a dictionary, in this case the order would be the order that values where inserted into the dictionary. Stores that instead store values in SPARQL-order can return an instance of ValueComparator which may allow for further optimizations.

Note that this method is experimental and may be changed or removed without notice.

Returns:

a comparator that matches the order of values in the store

getValueFactory

ValueFactory getValueFactory()

Gets a ValueFactory object that can be used to create IRI-, blank node- and literal objects.

Returns:

a ValueFactory object for this TripleSource.