you could separate your load process to two apps
one will load data from the DB and save the tables to QVDs
second will apply your logic and will have the user interface
in the management console you define the first app to load every 30 minutes
and the second to start when the first finish.
now if you apply your rule to the first one it'll be empty but the second will always be with data
because it'll load the last updated QVDS