Consistency Models(II) — Consistency & Consistency Levels(III) — Distributed Data Stores

In my last article, we delved into the different consistency models within Strong Consistency and how your application consistency guarantees vary within the different consistency models.

Let’s take a look at some other consistency models and the application guarantees with those models.

Session Consistency Models

Session consistency models guarantee consistency constraints for any client/application session. This level of consistency honours the client session. It ensures a strong consistency for an application session with the same session token. What that implies is that any write done during the session will be returned by the latest version for reads, from that same session. If reads happen from a different session, the above guarantee does not hold.

In summary, session consistency provides strong consistency for the session, ensuring the data stays up to date for any active read-write session. Session consistency allows you write latencies, availability, and read throughput comparable to that of eventual consistency but also provides strong consistency guarantees for the session.

Within Session Consistency, we have multiple models as well -