Technical GlossaryData Engineering and AI Infrastructure

Exactly-Once Semantics

A processing model that aims to guarantee each data event is logically handled exactly once by the system.

Exactly-once semantics is a critical goal in stream systems for controlling duplicates and processing errors. In distributed systems, network failures, retries, and redelivery are common, so guaranteeing true single processing is difficult. Achieving this usually requires coordinated support from infrastructure, transaction handling, and idempotent design. It is especially important for financial events, counters, and mission-critical workflows.