Why not use kafka as eventstore

When using Kafka as pipeline for event sourcing, people will ask why not use Kafka as event store instead of a database. It can persist events and keep it for as long as it requires.

There are several drawbacks in doing so.

• Kafka only guarantees at least one delivery and there are duplicates in the event store that cannot be removed.

• Due to immutability, there is no way to manipulate the event store when the application evolves and events need to be transformed.

• No place to persist snapshots of entities/aggregates and replay will become slower and slower.

• Given Kafka partitions are distributed and they are hard to manage and backup compare with databases.

Given above disadvantages, a database is used as event store instead in eventuate architecture.