Maintenance of views

In relational databases a view definition is a query against the database, and a view materialization is the result of applying the view definition to the current database A view materialization over a database may change as relations in the database undergo modificationsIn this paper a mechanism is proposed in which the view is materialized at all times The problem which this mechanism addresses is how to quickly update the view in response to database changes A structure is maintained which provides information useful in minimizing the amount of work caused by updatesMethods are presented for handling both general databases and the much simpler tree databases (also called acyclic database) In both cases adding or deleting a tuple can be performed in polynomial time For tree databases the degree of the polynomial is independent of the schema structure while for cyclic databases the degree depends on the schema structure The cost of a sequence of tuple additions (deletions) is also analyzed