PREFER's demo

The following applet uses the pipelined algorithm of PREFER to perform ranked queries on a synthetic houses database. The relation has 50,000 tuples. The applet is best viewed with Internet Explorer (we have tested it using IE 5, 6).

If the checkbox below is not checked then the query is executed by the DBMS using plain SQL. Otherwise, PREFER's algorithm retrieves a small number (as many as are necessary for the algorithm to produce the desired output) of tuples from one of the materialized views (we created 34 materialized views) of the database . Then these tuples are processed locally and are output in the correct order. Notice that the applet performs poorly in the case of slow internet connections. Also notice that the first query that you execute may take a little more time, because it loads the Oracle drivers.