Package org.apache.derby.vti

Interface IFastPath

  • public interface IFastPath
    An internal api for VTIs to allow VTI's written in terms of the datatype system, e.g. returning rows. This allows passing of data from the VTI into the query engine without a conversion through a JDBC ResultSet.

    • Field Summary

      Fields 
      Modifier and Type Field Description
      static int GOT_ROW
      Indicates nextRow() found a row..
      static int NEED_RS
      Indicates nextRow() has completed its scan but executeQuery must be called to complete the query.
      static int SCAN_COMPLETED
      Indicates nextRow() has completed its scan.

    • Field Detail

      • SCAN_COMPLETED

        static final int SCAN_COMPLETED
        Indicates nextRow() has completed its scan.
        See Also:
        Constant Field Values

      • NEED_RS

        static final int NEED_RS
        Indicates nextRow() has completed its scan but executeQuery must be called to complete the query.
        See Also:
        Constant Field Values

    • Method Detail

      • executeAsFastPath

        boolean executeAsFastPath()
                   throws StandardException,
                          java.sql.SQLException
        Start a query. Returns true if the VTI will start out as a fast path query and thus rows will be returned by nextRow(). Returns false if the engine must call the VTI's PreparedStatement.executeQuery() method to execute as a regular ResultSet VTI.
        Throws:
        StandardException
        java.sql.SQLException

      • nextRow

        int nextRow​(DataValueDescriptor[] row)
     throws StandardException,
            java.sql.SQLException
        When operating in fast path mode return the next row into the passed in row parameter. Returns GOT_ROW if a valid row is found. Returns SCAN_COMPLETED if the scan is complete. Returns NEED_RS if the rest of the query must be handled as a regular ResultSet VTI by the engine calling the VTI's PreparedStatement.executeQuery()
        Throws:
        StandardException
        java.sql.SQLException

      • currentRow

        void currentRow​(java.sql.ResultSet rs,
                DataValueDescriptor[] row)
         throws StandardException,
                java.sql.SQLException
        A call from the VTI execution layer back into the supplied VTI. Presents the row just processed as an array of DataValueDescriptors. This only called when the VTI is being executed as a regular ResultSet VTI
        Throws:
        StandardException
        java.sql.SQLException

      • rowsDone

        void rowsDone()
       throws StandardException,
              java.sql.SQLException
        Called once the ResultSet returned by executeQuery() has emptied all of its rows (next() has returned false).
        Throws:
        StandardException
        java.sql.SQLException