Event sourcing: append-only architecture processing 10K events/sec with complete history, time travel debugging, and CQRS. From theory to production implementation.
Key Takeaways Event sourcing provides complete audit trail and time-travel debugging capabilities
CQRS separation enables independent scaling of reads and writes
Snapshots are essential for performance with large event streams
Proper event versioning and migration strategies prevent production disasters
Event streaming with Kafka enables real-time projections and system integration
Why Event Sourcing?
Your database shows current state. But how did it get there? Who changed what? When? Why?
-- Traditional: Current state only SELECT balance FROM accounts WHERE id = 123; -- Result: 1000 -- Event sourced: Complete history SELECT * FROM events WHERE aggregate_id = 123; -- Shows every deposit, withdrawal, fee, interest
We needed audit trail for financial compliance. Event sourcing gave us that plus time travel, debugging superpowers, and perfect scalability.
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