Data as a continuous flow.
WHAT AN EVENT IS
A record that something happened, at a point in time.
WHAT AN EVENT STREAM IS
An ordered, append-only sequence of such records.
WHAT MAKES IT DIFFERENT FROM A QUEUE
Records are retained after consumption, and several consumers read independently.
WHAT THAT ENABLES
Replaying history New consumers reading from the beginning Several systems consuming the same events
WHAT A TOPIC IS
A named stream of related events.
WHAT A PARTITION IS
A subdivision of a topic, processed independently.
WHY PARTITIONS EXIST
They allow parallel consumption, which is how throughput scales.
WHAT ORDERING IS GUARANTEED WITHIN
A partition, not a topic.
WHY THAT MATTERS ENORMOUSLY
Events for one entity must share a partition, or they may be processed out of order.
WHAT DETERMINES THE PARTITION
A key, usually the entity identifier.
WHAT AN OFFSET IS
A consumer's position in a partition.
WHERE IT IS STORED
By the platform, or by the consumer.
WHAT THAT DETERMINES
Whether a restarted consumer resumes correctly.
