Event Sourcing

1. What Is Event Sourcing?

A software architecture pattern based on events.

Persist the system’s CUD events.

2. Why Is Event Sourcing Needed?

Traditional CRUD has some problems:

1. It directly operates on the database, whose performance is relatively low.
2. To prevent concurrency problems, locks, transactions, and so on need to be introduced, causing performance loss.
3. Because data storage usually stores only the final state of the data, additional auditing mechanisms are needed to track the history of data changes.

How does event sourcing solve these problems?

1. Introduce a message queue for asynchronous processing.
3. Events are immutable + generate and store events for CUD operations. They can be used to replay the system to any state.

3. Disadvantages of Event Sourcing

• The storage consumed by events may be very large.
• Only eventual consistency can be achieved.

4. How to Design Event Sourcing

5. References

• Event Sourcing | Newbe.Claptrap
• From Event Sourcing to Event-Driven: A Review of Event and Event-Stream Technologies | Leon Lu