SA-301a · Module 1

Event Sourcing Pitfalls

3 min read

Event sourcing is powerful and unforgiving. The pattern rewards disciplined implementation and punishes shortcuts with compounding complexity. I have seen three pitfalls consistently across engagements — not because teams are careless, but because the pitfalls look reasonable until the scale reveals them.

Do This

  • Design events as business facts, not technical artifacts — "OrderPlaced" not "InsertOrderRecord"
  • Version event schemas from day one and build upcasters before you need them
  • Define explicit retention and archival policies for event streams — storage is cheap but replay performance is not

Avoid This

  • Store events that mirror CRUD operations — that is a change log, not event sourcing, and you lose the semantic meaning
  • Allow event schema changes without versioning — you will corrupt replay for every consumer
  • Assume event streams can grow unbounded — without snapshots and archival, replay latency grows linearly with history