Interface DatabaseInterface

    • Method Summary

      All Methods Instance Methods Abstract Methods 
      Modifier and Type Method Description
      void dispose()
      Called when the connection is disposed.
      void disposeResult​(int result_id)
      Disposes of a result of a query on the server.
      void disposeStreamableObject​(int result_id, long streamable_object_id)
      Disposes a streamable object channel with the given identifier.
      QueryResponse execQuery​(SQLQuery sql)
      Executes the query and returns a QueryResponse object that describes the result of the query.
      ResultPart getResultPart​(int result_id, int row_number, int row_count)
      Returns a part of a result set.
      StreamableObjectPart getStreamableObjectPart​(int result_id, long streamable_object_id, long offset, int len)
      Returns a section of a large binary or character stream in a result set.
      boolean login​(java.lang.String default_schema, java.lang.String username, java.lang.String password, DatabaseCallBack call_back)
      Attempts to log in to the database as the given username with the given password.
      void pushStreamableObjectPart​(byte type, long object_id, long object_length, byte[] buf, long offset, int length)
      Pushes a part of a streamable object from the client onto the server.
    • Method Detail

      • login

        boolean login​(java.lang.String default_schema,
                      java.lang.String username,
                      java.lang.String password,
                      DatabaseCallBack call_back)
               throws java.sql.SQLException
        Attempts to log in to the database as the given username with the given password. Only one user may be authenticated per connection. This must be called before the other methods are used.

        A DatabaseCallBack implementation must be given here that is notified of all events from the database. Events are only received if the login was successful.

        Throws:
        java.sql.SQLException
      • pushStreamableObjectPart

        void pushStreamableObjectPart​(byte type,
                                      long object_id,
                                      long object_length,
                                      byte[] buf,
                                      long offset,
                                      int length)
                               throws java.sql.SQLException
        Pushes a part of a streamable object from the client onto the server. The server stores the large object for use with a future query. For example, a sequence of with a query with large objects may operate as follows;

         1) Push 100 MB object (id = 104)
         2) execQuery with query that contains a streamable object with id 104
         

        Note that the client may push any part of a streamable object onto the server, however the streamable object must have been completely pushed for the query to execute correctly. For example, an 100 MB byte array may be pushed onto the server in blocks of 64K (in 1,600 separate blocks).

        Parameters:
        type - the StreamableObject type (1 = byte array, 2 = char array)
        object_id - the identifier of the StreamableObject for future queries.
        object_length - the total length of the StreamableObject.
        buf - the byte[] array representing the block of information being sent.
        offset - the offset into of the object of this block.
        length - the length of the block being pushed.
        Throws:
        java.sql.SQLException
      • execQuery

        QueryResponse execQuery​(SQLQuery sql)
                         throws java.sql.SQLException
        Executes the query and returns a QueryResponse object that describes the result of the query. The QueryResponse object describes the number of rows, describes the columns, etc. This method will block until the query has completed. The QueryResponse can be used to obtain the 'result id' variable that is used in subsequent queries to the engine to retrieve the actual result of the query.
        Throws:
        java.sql.SQLException
      • getResultPart

        ResultPart getResultPart​(int result_id,
                                 int row_number,
                                 int row_count)
                          throws java.sql.SQLException
        Returns a part of a result set. The result set part is referenced via the 'result id' found in the QueryResponse. This is used to read parts of the query once it has been found via 'execQuery'.

        The returned List object contains the result requested.

        If the result contains any StreamableObject objects, then the server allocates a channel to the object via the 'getStreamableObjectPart' and the identifier of the StreamableObject. The channel may only be disposed if the 'disposeStreamableObject' method is called.

        Throws:
        java.sql.SQLException
      • disposeResult

        void disposeResult​(int result_id)
                    throws java.sql.SQLException
        Disposes of a result of a query on the server. This frees up server side resources allocated to a query. This should be called when the ResultSet of a query closes. We should try and use this method as soon as possible because it frees locks on tables and allows deleted rows to be reclaimed.
        Throws:
        java.sql.SQLException
      • getStreamableObjectPart

        StreamableObjectPart getStreamableObjectPart​(int result_id,
                                                     long streamable_object_id,
                                                     long offset,
                                                     int len)
                                              throws java.sql.SQLException
        Returns a section of a large binary or character stream in a result set. This is used to stream large values over the connection. For example, if a row contained a multi megabyte object and the client is only interested in the first few characters and the last few characters of the stream. This would require only a few queries to the database and the multi- megabyte object would not need to be downloaded to the client in its entirety.
        Throws:
        java.sql.SQLException
      • disposeStreamableObject

        void disposeStreamableObject​(int result_id,
                                     long streamable_object_id)
                              throws java.sql.SQLException
        Disposes a streamable object channel with the given identifier. This should be called to free any resources on the server associated with the object. It should be called as soon as possible because it frees locks on the tables and allows deleted rows to be reclaimed.
        Throws:
        java.sql.SQLException
      • dispose

        void dispose()
              throws java.sql.SQLException
        Called when the connection is disposed. This will terminate the connection if there is any connection to terminate.
        Throws:
        java.sql.SQLException