Online Feature Store

An online feature store is designed to serve the required features at prediction time with millisecond-level latency. This layer is especially important for real-time decision systems, recommendation engines, and risk scoring workflows. Performance, availability, and consistency are the top priorities here. If the feature definition used in training is calculated differently in production, model quality can degrade significantly. For that reason, online store design is not only a speed problem, but also a correctness problem.