Package org.eclipse.rdf4j.federated

Class QueryManager

java.lang.Object
org.eclipse.rdf4j.federated.QueryManager
public class QueryManager extends Object
QueryManager to manage queries. a) Management of running queries (abort, finish) b) Factory to create queries
Author:
Andreas Schwarte

  • Constructor Details

    • QueryManager

      public QueryManager()

  • Method Details

    • init

      public void init(FedXRepository repo, FederationContext federationContext)

    • shutdown

      public void shutdown()

    • registerQuery

      public void registerQuery(QueryInfo queryInfo)
      Add the query to the set of running queries, queries are identified via a unique id
      Parameters:
      queryInfo -

    • getRunningQueries

      public Set<QueryInfo> getRunningQueries()

    • getNumberOfRunningQueries

      public int getNumberOfRunningQueries()

    • abortQuery

      public void abortQuery(QueryInfo queryInfo)

    • finishQuery

      public void finishQuery(QueryInfo queryInfo)

    • isRunning

      public boolean isRunning(QueryInfo queryInfo)

    • addPrefixDeclaration

      public void addPrefixDeclaration(String prefix, String namespace)
      Register a prefix declaration to be used during query evaluation. If a known prefix is used in a query, it is substituted in the parsing step. If namespace is null, the corresponding entry is removed.
      Parameters:
      prefix - a common prefix, e.g. rdf
      namespace - the corresponding namespace, e.g. "http://www.w3.org/1999/02/22-rdf-syntax-ns#"

    • prepareTupleQuery

      public TupleQuery prepareTupleQuery(String queryString) throws MalformedQueryException
      Prepare a tuple query which uses the underlying federation to evaluate the query.

      The queryString is modified to use the declared PREFIX declarations, see FedXConfig.getPrefixDeclarations() for details.

      Parameters:
      queryString -
      Returns:
      the prepared tuple query
      Throws:
      MalformedQueryException

    • prepareGraphQuery

      public GraphQuery prepareGraphQuery(String queryString) throws MalformedQueryException
      Prepare a tuple query which uses the underlying federation to evaluate the query.

      The queryString is modified to use the declared PREFIX declarations, see FedXConfig.getPrefixDeclarations() for details.

      Parameters:
      queryString -
      Returns:
      the prepared graph query
      Throws:
      MalformedQueryException

    • prepareBooleanQuery

      public BooleanQuery prepareBooleanQuery(String queryString) throws MalformedQueryException
      Prepare a boolean query which uses the underlying federation to evaluate the query.

      The queryString is modified to use the declared PREFIX declarations, see FedXConfig.getPrefixDeclarations() for details.

      Parameters:
      queryString -
      Returns:
      the prepared BooleanQuery
      Throws:
      MalformedQueryException

    • prepareQuery

      public Query prepareQuery(String queryString) throws MalformedQueryException
      Prepare a Query which uses the underlying federation to evaluate the SPARQL query.

      The queryString is modified to use the declared PREFIX declarations, see FedXConfig.getPrefixDeclarations() for details.

      Parameters:
      queryString -
      Returns:
      the prepared Query
      Throws:
      MalformedQueryException

    • getQueryPlan

      public String getQueryPlan(String queryString) throws MalformedQueryException, FedXException
      Retrieve the query plan for the given query string.
      Parameters:
      queryString -
      Returns:
      the query plan
      Throws:
      MalformedQueryException
      FedXException

    • getNextQueryId

      public BigInteger getNextQueryId()
      Computes the (incremental) next query identifier. Implementation is thread safe and synchronized.
      Returns:
      the next query identifier

    • getPrefixDeclarations

      protected String getPrefixDeclarations()
      Get the prefix declarations that have to be prepended to the query.
      Returns:
      the prefix declarations

    • getPrefixDeclarationsCheck

      protected String getPrefixDeclarationsCheck(String queryString)
      Get the prefix declarations that have to be added while considering prefixes that are already declared in the query. The issue here is that duplicate declaration causes exceptions in RDF4J.
      Parameters:
      queryString -
      Returns:
      the prefix declarations

    • findQueryPrefixes

      protected static Set<String> findQueryPrefixes(String queryString)
      Find all prefixes declared in the query
      Parameters:
      queryString -
      Returns:
      the prefixes