These rules look for certain conditions to occur in the data. When these conditions are satisfied, the rules wake up and fire. When a rule fires, it executes its action, which normally is a script of database commands, or a call to an external application program. Active database systems can help make it easier to develop application systems that perform monitoring and alerting as data in a database changes. Active database technology can also improve the performance of these types of applications.
Views are functions that derive data from stored data in a database.
Normally, a view is expressed as a query that generates a derived table from some stored data tables. The normal way that queries against views are processed is to perform query modification, essentially macro-expanding a query until it no longer refers to any views. But clearly, if a view is expensive to compute, and is queried frequently and updated only infrequently, then materializing it as a stored table and incrementally maintaining it becomes an attractive option. Potential Related Projects Related projects might involve optimized materialized view maintenance as well as optimized testing of triggers with more sophisticated conditions involving user-defined functions and aggregates.