How do application update processes differ when using Deployment and StatefulSet in Kubernetes?

In Kubernetes, Deployment and StatefulSet are used to manage different types of applications, and their update processes differ:

• Deployment is intended for stateless applications. During an update, Deployment creates new Pods with the new version and gradually removes the old ones (rolling update). This ensures continuous application operation without downtime.

• StatefulSet is used for stateful applications, where the order and stability of Pod names and their storage are important. The update of StatefulSet occurs sequentially: each Pod is updated one by one, starting from the last, and only after the previous one has been successfully updated. This guarantees the preservation of state and correct operation of applications requiring persistent identifiers.

Thus, Deployment provides parallel and rapid updates, while StatefulSet offers sequential and controlled updates, considering the application's state.