text: CREATE STREAM bids(t FLOAT, id INT, broker_id INT, volume FLOAT, price FLOAT)
    FROM FILE 'examples/data/finance.csv'
    LINE DELIMITED orderbook (book := 'bids', brokers := '10', 
                              deterministic := 'yes');
  
  CREATE STREAM asks(t FLOAT, id INT, broker_id INT, volume FLOAT, price FLOAT)
    FROM FILE 'examples/data/finance.csv'
    LINE DELIMITED orderbook (book := 'asks', brokers := '10', 
                              deterministic := 'yes');
  
  SELECT b.broker_id, SUM(a.volume + (-1 * b.volume)) AS axfinder
  FROM   bids b, asks a
  WHERE  b.broker_id = a.broker_id
    AND  ( (a.price + ((-1) * b.price) > 1000) OR
           (b.price + ((-1) * a.price) > 1000) )
  GROUP BY b.broker_id;
  