The Java SqlAggregator Class

 
    public  class SqlAggregator implements SqlConnection, java.io.Closeable
    {
        /**
        * Constructor of the SQL aggregating.
        * @param engines a list of engines used to aggregate
        */
        public SqlAggregator(SqlLocalConnection [] engines) 
        {
            init(engines, 64*1024);
        }
        public SqlAggregator(SqlLocalConnection [] engines, long bufferSize) 
        {
            init(engines, bufferSize);
        }
        private void init(SqlLocalConnection [] engines, long bufferSize)
        {
            long [] _engines = new long[engines.length];
            for (int i = 0; i < engines.length; i++) 
            {
                _engines[i] = engines[i].getEngine();
            }
            agg = open(_engines, bufferSize);
        }
 
        /**
        * Execute SQL query.
        * @param query SQL query with '?' used as parameter placeholder.
        * @return cursor through selected tuples
        */
        public SqlResultSet executeQuery(String query, Object... params) 
        {
            if (result != null) 
            {
                result.close();
            }
            return result = new SqlResultSet(this, executeQuery(agg, query, params));
        }
 
        /**
        * Execute SQL update statement
        * @param stmt SQL DML statement with '?' used as parameter placeholder.
        * @return number of affected (updated, inserted, deleted) records
        */
        public int executeStatement(String stmt, Object... params) 
        {
            return executeStatement(agg, stmt, params);
        }
        public void detachResultSet(SqlResultSet res) 
        {
            result = null;
        }
 
        private long agg;
         
        /**
        * Close this connection.
        */
        public void disconnect() 
        {
            close(agg);
        }
 
        /**
        * Close this connection. The same as disconnect.
        */
        public void close() 
        {
            disconnect();
        }
    };