What happens to data visibility in the Session Consistency option?

Session Consistency is a specific consistency model that ensures within a single session, an application will see the changes it has made in a specific order, providing a reliable view of the data. This means that if an application performs a write operation, that application will be able to immediately read that data back within the same session, thereby providing a sense of state and order to operations that occur during that session.

However, this state does not extend beyond the session itself. Other applications or sessions may not see these updates until the data is fully propagated across the system. This is particularly important in distributed systems where multiple clients may be interacting with the same dataset simultaneously. By ensuring that each session has a coherent view of the updates it has made, but not enforcing this coherence across all sessions, session consistency strikes a balance between performance and reliability.

The characteristics of the other options illustrate different consistency models that do not fully align with the behavior described by session consistency. For example, some models might allow for immediate visibility of changes across all applications or eventually consistent behavior without guaranteeing the order of visibility, which is not the case with session consistency.