Do we really need a separate event store with Event Sourcing and CQRS patterns?

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Suppose we have a situation when we need to implement some domain rules that requires examination of object history (event store). For example we have an Order object with CurrentStatus property, and we need to examine Order. CurrentStatus changes history.

Most likely you will answer that I need to move this knowledge to domain and introduce Order. StatusHistory property that contains a collection of status records, and that I should not query event store. And I will agree with you.

What I question is the need of Event Store. We write in event store events that has business meaning (domain value), we do not record UserMovedMouse events (in most cases). And as with OrderStatusChanged event there is a high chance that most of events from EventStore will be needed at some point for domain logic, and we end up with a domain object that have a EventHistory property with the collection of events.

I can see a value in separate event store for patterns such as CQRS when you have a single write only event store and multiple read only query stores, which gives you some scalability. However the need to to introduce such thing in code is in question too for me. All decent databases support single write server, multiple read servers scalability (master-slave replication).

Why should I introduce such thing at source code level? Why not to forget about Web Services, and Message buses and use write your own wrapers around Sockets. I have a great respect to "old school" DDD as it was described be Eric Evans, and I see some fresh and good ideas in new wave DDD+SQRC+EventSourcing pattern aggregate.

However the main idea of CQRS is under big question for me. Am I missing something? Domain-driven-design cqrs event-sourcing link|improve this question asked 27 mins agoAlex Burtsev1,654620 85% accept rate.

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