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by geoduck14 1667 days ago
I've never heard of the term Event Sourcing. I AM familiar with Event Streaming. Some of what this article talks about surprised me - and I think it is because I don't fully understand the difference between Event Sourcing and Event Streaming.

Is this article a fine summary?: https://developer.confluent.io/learn-kafka/event-sourcing/ev...
1 comments
bruth 1667 days ago
I have not watched that clip, but as I said above, Confluent isn't a good resource for defining this term since Kafka cannot be used to do ES. I would suggest an article like: https://domaincentric.net/blog/eventstoredb-vs-kafka

Also refer to the list of great resources @oskar_dudycz posted in another comment: https://github.com/oskardudycz/EventSourcing.NetCore#1319-th...

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claytonjy 1667 days ago
that first article finds only one issue with Kafka-for-ES: limited number of partitions. Use pulsar, problem solved? Doesn't have the support or ecosystem of Kafka, but surely more than eventstoreDB.
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gunnarmorling 1667 days ago
There's two main reasons why Kafka as of today isn't a good fit for implementing event sourcing:

- Lacking support for key-based look-ups: when trying to materialize the current state of an entity, you cannot query Kafka efficiently for just those events (a partition-per-entity strategy doesn't scale due to the partion number limitation, which may change with KRaft in the future)

- Lacking support for (optimistic) locking: you cannot make sure to reject events based on outdated state, unless you apply work-arounds like a single writer architecture

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bruth 1667 days ago
They aren't solving the same problem. An event sourced entity (should) have a very small scope. It acts as a consistency boundary around some bit of state. Each event in "the stream" for that entity represents a state change. This is analogous to a database row which represents the _current_ state of the entity being modeled for that table.

Like a table, there can be an arbitrary number of rows (>millions), thus you could have millions of event streams. You can't have millions of Kafka partitions. The scope/scale of a Kafka partition is not designed for that small granularity.

Again, I have no issue with Kafka and I think Pulsar is superior in the event streaming/platform space. I also the Kafka ecosystem is impressive and I love listening Confluent Cloud podcast! But it is not designed for this use case.

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