Anti-pattern: unnecessary persistence

Making things persist that don't need to persist is an anti-pattern. This is because persistence is extremely onerous. For example:

• persistence involves I/O to secondary storage and costs space and time
• persistence requires schema evolution
• persistence complicates data consistency in distributed systems
• persistence increases code complexity
• persistence increases the number of test scenarios and therefore complicates testing
• persistence complicates error handling
• persistence complicates crash recovery
• persistence complicates concurrency

Just taking one of these: (data consistency). Persistence is an enormous burden (both in terms of performance and code complexity) for ensuring the system recovers to a consistent cut. See Consistent Global States of Distributed Systems: Fundamental Concepts and Mechanisms

Schema evolution is extremely onerous:

Do you, Programmer, take this Object to be part of the persistent state of your application, to have and to hold, through maintenance and iterations, for past and future versions, as long as the application shall live?

(--Arturo Bejar, [ref StateBundles] see In Praise of Manual Persistence)