CQRS without Event Sourcing - what are the drawbacks?

Question

Besides missing some of the benefits of Event Sourcing, are there any other drawbacks to adapting an existing architecture to CQRS without the Event Sourcing piece?

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Answer 1

There is a fundamental problem of Event Sourcing pattern, that is the events in the Event Store may not be compatible with your event handlers in your application any more due to code change.

That being said, whenever you modify the event handler by adding new features, you need to think about the backward compatibility. You have to make sure your code can always handle the same event in different stage created by different version of your code.

When your application becomes more complex, you will find it really pain in the ass to make it backward compatible.