Event in Active Databases
Events in active databases are typically considered to be atomic and instantaneous, that is, they either happen or not. Events are either primitive or composite, that is, either they are part of the system (primitive) or they are specified in terms of other events (composite).
An event is a happening of interest that can invoke execution of reactive behavior, for example, trigger an ECA rule. Events in active databases are typically considered to be atomic and instantaneous [1, 3, 4], that is, they either happen or not. However, this leads to problems  addressed in the event specification entry.
Events can be classified as primitive or composite events. Primitive events refer to elementary occurrences that are predefined in the system. Primitive events are typically further categorized as database events, time events, transaction events, method events, etc. A composite event is a set of events matching an event specification.
Events can have attributes, that...
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