1.5. Processing Reliability

Storm provides two types of guarantees when processing tuples for a Storm topology.

 

Table 1.3. Processing Guarantees

Guarantee

Description

At least once

Reliable; Tuples are processed at least once, but may be processed more than once. Use when subsecond latency is required and for unordered idempotent operations.

Exactly once

Reliable; Tuples are processed only once. Requires the use of a Trident spout and the Trident API.