One of the most interesting aspects of the CQRS architecture is the ability to use event sourcing within your business applications. Representing all state changes as domain events has various benefits, not in the least being able to look back upon historical data to derive new information.
However, although historical information is nice, every system must also know its current state. Accessing the current state in traditional applications is just a database lookup. Can we do this in an event-based systems without adding a lot of complexity?