Stateless Stream Processing refers to computations on data streams where each incoming event is processed independently, without reference to or reliance on any information from previous events (no historical state). The output for a given input event is solely determined by the content of that event itself and the defined processing logic.
This is the simplest form of stream processing, contrasting with stateful stream processing which requires maintaining context across events.
In a stateless operation:
While simple and efficient, purely stateless processing is limited in the types of insights it can derive. Many real-world stream processing use cases require state to:
RisingWave supports stateless operations as fundamental building blocks within its SQL-based stream processing:
Even though RisingWave is a powerful stateful stream processing engine (excelling at materialized views, joins, and aggregations), these basic stateless operations are essential components of more complex streaming queries. They are often the first steps in a dataflow, preparing or cleaning data before it enters stateful operators.