Package org.apache.jena.sparql.exec

Class QueryExecDataset

  • All Implemented Interfaces:
    java.lang.AutoCloseable, QueryExec
    public class QueryExecDataset
extends java.lang.Object
implements QueryExec
    All the SPARQL query result forms at the graph-level.

    • Method Detail

      • close

        public void close()
        Description copied from interface: QueryExec
        Close the query execution and stop query evaluation as soon as convenient. QExec objects, and a RowSet from QueryExec.select(), can not be used once the QExec is closed. Model results from QueryExec.construct() and QueryExec.describe() are still valid.

        It is important to close query execution objects in order to release resources such as working memory and to stop the query execution. Some storage subsystems require explicit ends of operations and this operation will cause those to be called where necessary. No operations on the query execution or any associated result set are permitted after this call.

        Specified by:
        close in interface java.lang.AutoCloseable
        Specified by:
        close in interface QueryExec

      • isClosed

        public boolean isClosed()
        Description copied from interface: QueryExec
        Answer whether this QueryExecution object has been closed or not.
        Specified by:
        isClosed in interface QueryExec
        Returns:
        boolean

      • abort

        public void abort()
        Description copied from interface: QueryExec
        Stop in mid execution. This method can be called in parallel with other methods on the QueryExecution object. There is no guarantee that the concrete implementation actual will stop or that it will do so immediately. No operations on the query execution or any associated result set are permitted after this call and may cause exceptions to be thrown.
        Specified by:
        abort in interface QueryExec

      • select

        public RowSet select()
        Description copied from interface: QueryExec
        Execute a SELECT query

        Important: The name of this method is somewhat of a misnomer in that depending on the underlying implementation this typically does not execute the SELECT query but rather answers a wrapper over an internal data structure that can be used to answer the query. In essence calling this method only returns a plan for executing this query which only gets evaluated when you actually start iterating over the results.

        Specified by:
        select in interface QueryExec

      • construct

        public Graph construct​(Graph graph)
        Description copied from interface: QueryExec
        Execute a CONSTRUCT query, putting the statements into a graph.
        Specified by:
        construct in interface QueryExec
        Returns:
        Graph The graph argument for cascaded code.

      • constructTriples

        public java.util.Iterator<Triple> constructTriples()
        Description copied from interface: QueryExec
        Execute a CONSTRUCT query, returning the results as an iterator of Triple.

        Caution: This method may return duplicate Triples. This method may be useful if you only need the results for stream processing, as it can avoid having to place the results in a Model.

        Important: The name of this method is somewhat of a misnomer in that depending on the underlying implementation this typically does not execute the CONSTRUCT query but rather answers a wrapper over an internal data structure that can be used to answer the query. In essence calling this method only returns a plan for executing this query which only gets evaluated when you actually start iterating over the results.

        Specified by:
        constructTriples in interface QueryExec
        Returns:
        An iterator of Triple objects (possibly containing duplicates) generated by applying the CONSTRUCT template of the query to the bindings in the WHERE clause.

      • constructQuads

        public java.util.Iterator<Quad> constructQuads()
        Description copied from interface: QueryExec
        Execute a CONSTRUCT query, returning the results as an iterator of Quad.

        Caution: This method may return duplicate Quads. This method may be useful if you only need the results for stream processing, as it can avoid having to place the results in a Model.

        Specified by:
        constructQuads in interface QueryExec
        Returns:
        An iterator of Quad objects (possibly containing duplicates) generated by applying the CONSTRUCT template of the query to the bindings in the WHERE clause.

        See QueryExec.constructTriples() for usage and features.

      • constructDataset

        public DatasetGraph constructDataset​(DatasetGraph dataset)
        Description copied from interface: QueryExec
        Execute a CONSTRUCT query, putting the statements into 'dataset'. This may be an extended syntax query (if supported).
        Specified by:
        constructDataset in interface QueryExec

      • describe

        public Graph describe​(Graph graph)
        Description copied from interface: QueryExec
        Execute a DESCRIBE query, putting the statements into a graph.
        Specified by:
        describe in interface QueryExec
        Returns:
        Graph The model argument for cascaded code.

      • describeTriples

        public java.util.Iterator<Triple> describeTriples()
        Description copied from interface: QueryExec
        Execute a DESCRIBE query, returning the results as an iterator of Triple.

        Caution: This method may return duplicate Triples. This method may be useful if you only need the results for stream processing, as it can avoid having to place the results in a Model.

        Important: The name of this method is somewhat of a misnomer in that depending on the underlying implementation this typically does not execute the DESCRIBE query but rather answers a wrapper over an internal data structure that can be used to answer the query. In essence calling this method only returns a plan for executing this query which only gets evaluated when you actually start iterating over the results.

        Specified by:
        describeTriples in interface QueryExec
        Returns:
        An iterator of Triple objects (possibly containing duplicates) generated as the output of the DESCRIBE query.

      • ask

        public boolean ask()
        Description copied from interface: QueryExec
        Execute an ASK query
        Specified by:
        ask in interface QueryExec

      • execJson

        public JsonArray execJson()
        Description copied from interface: QueryExec
        Execute a JSON query and return a json array
        Specified by:
        execJson in interface QueryExec

      • execJsonItems

        public java.util.Iterator<JsonObject> execJsonItems()
        Description copied from interface: QueryExec
        Execute a JSON query and return an iterator
        Specified by:
        execJsonItems in interface QueryExec

      • getContext

        public Context getContext()
        Description copied from interface: QueryExec
        The properties associated with a query execution - implementation specific parameters This includes Java objects (so it is not an RDF graph). Keys should be URIs as strings. May be null (this implementation does not provide any configuration).
        Specified by:
        getContext in interface QueryExec

      • getDataset

        public DatasetGraph getDataset()
        Description copied from interface: QueryExec
        The dataset against which the query will execute. May be null - the dataset may be remote or the query itself has a dataset description.
        Specified by:
        getDataset in interface QueryExec

      • getQuery

        public Query getQuery()
        Description copied from interface: QueryExec
        The query associated with a query execution. May be null (QueryExec may have been created by other means)
        Specified by:
        getQuery in interface QueryExec

      • getQueryString

        public java.lang.String getQueryString()
        Description copied from interface: QueryExec
        The query as a string. This may be null (QueryExec may have been created by other means). This may contain non-Jena extensions and can not be parsed by Jena. If getQuery() is not null, this is a corresponding string that parses to the same query.
        Specified by:
        getQueryString in interface QueryExec