The funny thing about event sourcing is that most teams adopt it for the sexy parts (time travel, Kafka, sagas), but the thing that actually determines whether it survives contact with production is discipline around modeling and versioning.

You don’t pay the cost up front, you pay it 2 years in when the business logic has changed 5 times, half your events are “v2” or “DeprecatedFooHappened”, and you realize your “facts” about the past were actually leaky snapshots of whatever the code thought was true at the time. The hard part isn’t appending events, it’s deciding what not to encode into them so you can change your mind later without a migration horror show.

There’s also a quiet tradeoff here: you’re swapping “schema complexity + migrations” for “event model complexity + replay semantics”. In a bank-like domain that genuinely needs an audit trail, that trade is usually worth it. In a CRUD-ish SaaS where the real requirement is “be able to see who edited this record”, a well-designed append-only table with explicit revisions gets you 80% of the value at 20% of the operational and cognitive overhead.

Using Postgres as the event store is interesting because it pushes against the myth that you need a specialized log store from day one. But it also exposes the other myth: that event sourcing is primarily a technical choice. It isn’t. It’s a commitment to treat “how the state got here” as a first-class part of the domain, and that cultural/organizational shift is usually harder than wiring up SaveEvents and a Kafka projection.

I would upvote this comment more if I could.

I already refrained from introducing event sourcing to tackle wierd dependecies multiple time just by justaposing the amount of discipline that the team has that lead to the current state vs the discipline that is required to keep the event source solution going.

This comment just made it finally click for me why event sourcing sounds so good on paper but rarely seems to work out for real-world projects: it expects a level of correct-design-up-front which isn't realistic for most teams.