[mrsmrtss]

Yes, I don't know where the misconception that CQRS or Event Sourcing automatically means eventual consistency comes from. We have built, run, evolved, and operated quite a few reasonably sized event sourced systems successfully, and these systems are running to this day without any major incidents. We added eventually consistent projections where performance justified it, fully aware of the implications, but kept most of the system synchronous.

[anthonylevine]

I think people lump CQRS, Event Sourcing, and event-driven into this a single concept and then use those words interchangeably.

[andersmurphy]

Yup. It's a shame as amazing as event sourcing is it does come with complexity.

On the other hand CQRS + single writer pattern on their owncan be a massive performance win because it allows for efficient batching of views and updates. It's also much simpler to implement than a fullblown event sourcing system.

[mrkeen]

If you segregate your read and write, i.e put a (P)artition between them, and require writes to be (A)vailable when reads are down (and vice-versa), then you're either inconsistent, or eventually-consistent.