Introduction to Event Sourcing

Most services store only the current state of their data. An order row holds the latest status. A balance column holds the latest number. Event sourcing works differently: it stores every change, and computes the state from those changes.

What the Pattern Says

Event sourcing stores every change as an event. An event is a small immutable record of one fact that happened. Immutable means the record can never be changed after it is written. Events are named in the past tense, such as MoneyDeposited or OrderShipped.

Nothing is ever updated or deleted in place