Module org.apache.jena.arq
Package org.apache.jena.sparql.exec

Class QueryExecutionAdapter

java.lang.Object
org.apache.jena.sparql.exec.QueryExecutionAdapter
All Implemented Interfaces:
AutoCloseable, QueryExecution
Direct Known Subclasses:
QueryExecutionCompat, QueryExecutionHTTP
public class QueryExecutionAdapter extends Object implements QueryExecution
QueryExecution for a QueryExec working at the Graph-Node-Triple level.
See Also:

  • Method Details

    • adapt

      public static QueryExecution adapt(QueryExec qExec)

    • setInitialBinding

      public void setInitialBinding(Binding binding)
      Set the initial association of variables and values. May not be supported by all QueryExecution implementations.
      Specified by:
      setInitialBinding in interface QueryExecution
      Parameters:
      binding -

    • getDataset

      public Dataset getDataset()
      The dataset against which the query will execute. May be null, implying it is expected that the query itself has a dataset description.
      Specified by:
      getDataset in interface QueryExecution

    • getContext

      public Context getContext()
      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 QueryExecution

    • getQuery

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

    • getQueryString

      public String getQueryString()
      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 QueryExecution

    • execSelect

      public ResultSet execSelect()
      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:
      execSelect in interface QueryExecution

    • execConstruct

      public Model execConstruct()
      Execute a CONSTRUCT query
      Specified by:
      execConstruct in interface QueryExecution

    • execConstruct

      public Model execConstruct(Model model)
      Execute a CONSTRUCT query, putting the statements into a graph.
      Specified by:
      execConstruct in interface QueryExecution
      Returns:
      Graph The model argument for cascaded code.

    • execConstructTriples

      public Iterator<Triple> execConstructTriples()
      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:
      execConstructTriples in interface QueryExecution
      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.

    • execConstructQuads

      public Iterator<Quad> execConstructQuads()
      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.

      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 execConstructTriples() for usage and features.

      Specified by:
      execConstructQuads in interface QueryExecution
      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.

    • execConstructDataset

      public Dataset execConstructDataset()
      Execute a CONSTRUCT query, putting the statements into 'dataset'. This maybe an extended syntax query (if supported).
      Specified by:
      execConstructDataset in interface QueryExecution

    • execConstructDataset

      public Dataset execConstructDataset(Dataset dataset)
      Execute a CONSTRUCT query, putting the statements into 'dataset'. This may be an extended syntax query (if supported).
      Specified by:
      execConstructDataset in interface QueryExecution

    • execDescribe

      public Model execDescribe()
      Execute a DESCRIBE query
      Specified by:
      execDescribe in interface QueryExecution

    • execDescribe

      public Model execDescribe(Model model)
      Execute a DESCRIBE query, putting the statements into a graph.
      Specified by:
      execDescribe in interface QueryExecution
      Returns:
      Graph The model argument for cascaded code.

    • execDescribeTriples

      public Iterator<Triple> execDescribeTriples()
      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:
      execDescribeTriples in interface QueryExecution
      Returns:
      An iterator of Triple objects (possibly containing duplicates) generated as the output of the DESCRIBE query.

    • execAsk

      public boolean execAsk()
      Execute an ASK query
      Specified by:
      execAsk in interface QueryExecution

    • execJson

      public JsonArray execJson()
      Execute a JSON query and return a json array
      Specified by:
      execJson in interface QueryExecution

    • execJsonItems

      public Iterator<JsonObject> execJsonItems()
      Execute a JSON query and return an iterator
      Specified by:
      execJsonItems in interface QueryExecution

    • abort

      public void abort()
      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 QueryExecution

    • close

      public void close()
      Close the query execution and stop query evaluation as soon as convenient. QueryExecution objects, and a ResultSet from execSelect(), can not be used once the QueryExecution is closed. Model results from execConstruct() and execDescribe() 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 AutoCloseable
      Specified by:
      close in interface QueryExecution

    • isClosed

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

    • setTimeout

      public void setTimeout(long timeout, TimeUnit timeoutUnits)
      Set a timeout on the query execution. Processing will be aborted after the timeout (which starts when the appropriate exec call is made). Not all query execution systems support timeouts. A timeout of less than zero means no timeout.
      Specified by:
      setTimeout in interface QueryExecution
      See Also:

    • setTimeout

      public void setTimeout(long timeout)
      Set time, in milliseconds
      Specified by:
      setTimeout in interface QueryExecution
      See Also:

    • setTimeout

      public void setTimeout(long timeout1, TimeUnit timeUnit1, long timeout2, TimeUnit timeUnit2)
      Set timeouts on the query execution; the first timeout refers to time to first result, the second refers to overall query execution after the first result. Processing will be aborted if a timeout expires. Not all query execution systems support timeouts. A timeout of less than zero means no timeout; this can be used for timeout1 or timeout2.
      Specified by:
      setTimeout in interface QueryExecution

    • setTimeout

      public void setTimeout(long timeout1, long timeout2)
      Set time, in milliseconds
      Specified by:
      setTimeout in interface QueryExecution
      See Also:

    • getTimeout1

      public long getTimeout1()
      Return the first timeout (time to first result), in milliseconds: negative if unset
      Specified by:
      getTimeout1 in interface QueryExecution

    • getTimeout2

      public long getTimeout2()
      Return the second timeout (overall query execution after first result), in milliseconds: negative if unset
      Specified by:
      getTimeout2 in interface QueryExecution

    • setInitialBinding

      public void setInitialBinding(QuerySolution binding)
      Description copied from interface: QueryExecution
      Set the initial association of variables and values. May not be supported by all QueryExecution implementations.

      The preferred way is to use QueryExecutionDatasetBuilder.substitution(QuerySolution) which is supported uniformly for local and remote queries.

      Specified by:
      setInitialBinding in interface QueryExecution