Package org.eclipse.rdf4j.federated.evaluation

Class SparqlFederationEvalStrategy

java.lang.Object

org.eclipse.rdf4j.query.algebra.evaluation.impl.DefaultEvaluationStrategy

org.eclipse.rdf4j.query.algebra.evaluation.impl.StrictEvaluationStrategy

org.eclipse.rdf4j.federated.evaluation.FederationEvalStrategy

org.eclipse.rdf4j.federated.evaluation.SparqlFederationEvalStrategy

All Implemented Interfaces:

EvaluationStrategy, FederatedServiceResolver, FederatedServiceResolverClient

public class SparqlFederationEvalStrategy
extends FederationEvalStrategy

Implementation of a federation evaluation strategy which provides some special optimizations for SPARQL (remote) endpoints. The most important optimization is to used prepared SPARQL Queries that are already created using Strings.

Joins are executed using ControlledWorkerBoundJoin.

This implementation uses the SPARQL 1.1 VALUES operator for the bound-join evaluation

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Author:

Andreas Schwarte

Field Summary

Fields inherited from class org.eclipse.rdf4j.federated.evaluation.FederationEvalStrategy

cache, executor, federationContext

Fields inherited from class org.eclipse.rdf4j.query.algebra.evaluation.impl.DefaultEvaluationStrategy

dataset, serviceResolver, tripleSource

Constructor Summary

Constructors

Constructor	Description
SparqlFederationEvalStrategy(FederationContext federationContext)

Method Summary

Modifier and Type	Method	Description
CloseableIteration<BindingSet>	evaluateBoundJoinStatementPattern(StatementTupleExpr stmt, List<BindingSet> bindings)	Evaluate a bound join at the relevant endpoint, i.e.
protected CloseableIteration<BindingSet>	evaluateBoundJoinStatementPattern_UNION(StatementTupleExpr stmt, List<BindingSet> bindings)	Deprecated.
CloseableIteration<BindingSet>	evaluateExclusiveGroup(ExclusiveGroup group, BindingSet bindings)
CloseableIteration<BindingSet>	evaluateGroupedCheck(CheckStatementPattern stmt, List<BindingSet> bindings)	Perform a grouped check at the relevant endpoints, i.e.
CloseableIteration<BindingSet>	executeJoin(ControlledWorkerScheduler<BindingSet> joinScheduler, CloseableIteration<BindingSet> leftIter, TupleExpr rightArg, Set<String> joinVars, BindingSet bindings, QueryInfo queryInfo)	Execute the join in a separate thread using some join executor.

Methods inherited from class org.eclipse.rdf4j.federated.evaluation.FederationEvalStrategy

evaluate, evaluate, evaluate, evaluate, evaluate, evaluateArbitrayLengthPath, evaluateAtStatementSources, evaluateAtStatementSources, evaluateAtStatementSources, evaluateExclusiveTupleExpr, evaluateLeftJoin, evaluateNaryUnion, evaluateNJoin, evaluateService, evaluateService, evaluateSingleSourceQuery, evaluateZeroLengthPath, getMembersFromContext, getStatements, optimize, optimizeExclusiveExpressions, optimizeJoinOrder, performSourceSelection, performSourceSelection, precompile, precompile, prepare, prepare, prepare, prepare, prepare, prepareExclusiveTupleExpr, prepareLeftJoin, prepareNaryUnion, prepareNJoin, propagateServices

Methods inherited from class org.eclipse.rdf4j.query.algebra.evaluation.impl.DefaultEvaluationStrategy

evaluate, evaluate, evaluate, getCollectionFactory, getFederatedServiceResolver, getLimit, getQueryEvaluationMode, getService, getVarValue, isReducedOrDistinct, isTrue, isTrue, precompile, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, prepare, setCollectionFactory, setFederatedServiceResolver, setOptimizerPipeline, setQueryEvaluationMode, setTrackResultSize, setTrackTime, supplyBinaryValueEvaluation, supplyUnaryValueEvaluation

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.eclipse.rdf4j.query.algebra.evaluation.EvaluationStrategy

isTrackResultSize

Constructor Details

SparqlFederationEvalStrategy

public SparqlFederationEvalStrategy(FederationContext federationContext)

Method Details

evaluateBoundJoinStatementPattern

public CloseableIteration<BindingSet> evaluateBoundJoinStatementPattern(StatementTupleExpr stmt,
 List<BindingSet> bindings)
                                                                 throws QueryEvaluationException

Description copied from class: FederationEvalStrategy

Evaluate a bound join at the relevant endpoint, i.e. i.e. for a group of bindings retrieve results for the bound statement from the relevant endpoints

Specified by:

evaluateBoundJoinStatementPattern in class FederationEvalStrategy

Parameters:

stmt -

bindings -

Returns:

the result iteration

Throws:

QueryEvaluationException

evaluateBoundJoinStatementPattern_UNION

protected CloseableIteration<BindingSet> evaluateBoundJoinStatementPattern_UNION(StatementTupleExpr stmt,
 List<BindingSet> bindings)
                                                                          throws QueryEvaluationException

Deprecated.

Alternative evaluation implementation using UNION. Nowadays we use a VALUES clause based implementation

Throws:

QueryEvaluationException

evaluateGroupedCheck

public CloseableIteration<BindingSet> evaluateGroupedCheck(CheckStatementPattern stmt,
 List<BindingSet> bindings)
                                                    throws QueryEvaluationException

Description copied from class: FederationEvalStrategy

Perform a grouped check at the relevant endpoints, i.e. for a group of bindings keep only those for which at least one endpoint provides a result to the bound statement.

Specified by:

evaluateGroupedCheck in class FederationEvalStrategy

Parameters:

stmt -

bindings -

Returns:

the result iteration

Throws:

QueryEvaluationException

executeJoin

public CloseableIteration<BindingSet> executeJoin(ControlledWorkerScheduler<BindingSet> joinScheduler,
 CloseableIteration<BindingSet> leftIter,
 TupleExpr rightArg,
 Set<String> joinVars,
 BindingSet bindings,
 QueryInfo queryInfo)
                                           throws QueryEvaluationException

Description copied from class: FederationEvalStrategy

Execute the join in a separate thread using some join executor. Join executors are for instance: - SynchronousJoin - SynchronousBoundJoin - ControlledWorkerJoin - ControlledWorkerBoundJoin For endpoint federation use controlled worker bound join, for local federation use controlled worker join. The other operators are there for completeness. Use FederationEvalStrategy.executor to execute the join (it is a runnable).

Specified by:

executeJoin in class FederationEvalStrategy

Parameters:

joinScheduler -

leftIter -

rightArg -

joinVars -

bindings -

Returns:

the result

Throws:

QueryEvaluationException

evaluateExclusiveGroup

public CloseableIteration<BindingSet> evaluateExclusiveGroup(ExclusiveGroup group,
 BindingSet bindings)
                                                      throws RepositoryException,
MalformedQueryException,
QueryEvaluationException

Specified by:

evaluateExclusiveGroup in class FederationEvalStrategy

Throws:

RepositoryException

MalformedQueryException

QueryEvaluationException