AI engineering glossary · Data engineering
What is exactly-once semantics?
Exactly-once semantics: A guarantee that each event affects the result one time, even when failures and retries occur. It is usually achieved by combining at-least-once delivery with idempotent or transactional writes rather than by delivering each message once.
Exactly-once semantics: an example
After a crash and retry, a payment event is not counted twice in the account balance.
Related terms
More Data engineering terms
Where you learn it
Exactly-once semantics is part of the AI Engineering Program, which teaches it with notes, a hands-on lab and an exam. The first lesson is free.