Package org.eclipse.rdf4j.repository.sparql.query

Class SPARQLGraphQuery

java.lang.Object

org.eclipse.rdf4j.query.impl.AbstractOperation

org.eclipse.rdf4j.query.impl.AbstractQuery

org.eclipse.rdf4j.http.client.query.AbstractHTTPQuery

org.eclipse.rdf4j.repository.sparql.query.SPARQLGraphQuery

All Implemented Interfaces:

GraphQuery, Operation, Query

public class SPARQLGraphQuery
extends AbstractHTTPQuery
implements GraphQuery

Parses RDF results in the background.

Author:

James Leigh, Andreas Schwarte

Nested Class Summary

Nested classes/interfaces inherited from interface org.eclipse.rdf4j.query.Query

Query.QueryType

Field Summary

Fields inherited from class org.eclipse.rdf4j.http.client.query.AbstractHTTPQuery

baseURI, queryLanguage, queryString

Fields inherited from class org.eclipse.rdf4j.query.impl.AbstractOperation

bindings, dataset, includeInferred

Constructor Summary

Constructors

Constructor	Description
SPARQLGraphQuery(SPARQLProtocolSession httpClient, String baseURI, String queryString)

Method Summary

Modifier and Type	Method	Description
GraphQueryResult	evaluate()
void	evaluate(RDFHandler handler)
Explanation	explain(Explanation.Level level)	Explain how the query will be (or has been) executed/evaluated by returning an explanation of the query plan.

Methods inherited from class org.eclipse.rdf4j.http.client.query.AbstractHTTPQuery

getBindingsArray, getHttpClient, setMaxExecutionTime, toString

Methods inherited from class org.eclipse.rdf4j.query.impl.AbstractQuery

getMaxQueryTime, setMaxQueryTime

Methods inherited from class org.eclipse.rdf4j.query.impl.AbstractOperation

clearBindings, getBindings, getDataset, getIncludeInferred, getMaxExecutionTime, removeBinding, setBinding, setDataset, setIncludeInferred

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.eclipse.rdf4j.query.Operation

clearBindings, getBindings, getDataset, getIncludeInferred, getMaxExecutionTime, removeBinding, setBinding, setDataset, setIncludeInferred, setMaxExecutionTime

Methods inherited from interface org.eclipse.rdf4j.query.Query

getMaxQueryTime, setMaxQueryTime

Constructor Detail

SPARQLGraphQuery

public SPARQLGraphQuery(SPARQLProtocolSession httpClient,
                        String baseURI,
                        String queryString)

Method Detail

evaluate

public GraphQueryResult evaluate()
                          throws QueryEvaluationException

Specified by:

evaluate in interface GraphQuery

Throws:

QueryEvaluationException

evaluate

public void evaluate(RDFHandler handler)
              throws QueryEvaluationException,
                     RDFHandlerException

Specified by:

evaluate in interface GraphQuery

Throws:

QueryEvaluationException

RDFHandlerException

explain

public Explanation explain(Explanation.Level level)

Description copied from interface: Query

Explain how the query will be (or has been) executed/evaluated by returning an explanation of the query plan.

This method is useful for understanding why a particular query is slow. The most useful level is Executed, but this takes as long as it takes to execute/evaluate the query.

When timing a query you should keep in mind that the query performance will vary based on how much the JIT compiler has compiled the code (C1 vs C2) and based on what is or isn't cached in memory. If Timed explanations are considerably slower than Executed explanations the overhead with timing the query may be large on your system and should not be trusted.

WARNING: This method is experimental and is subject to change or removal without warning. Same goes for the returned explanation. There is currently only partial support for this method in RDF4J and and UnsupportedOperationException where support is lacking.

Specified by:

explain in interface Query

Parameters:

level - The explanation level that should be used to create the explanation. Choose between: Unoptimized (as parsed without optimizations) , Optimized (as is actually going to be used), Executed (as was executed/evaluated, including some real performance metrics), Timed (as was executed/evaluated including all real performance metrics). Executed and Timed level can potentially be slow.

Returns:

The explanation that we generated, which can be viewed in a human readable format with toString(), as JSON or as a simplified query plan object structure.