MQTT Brokers Cannot Replace Historians in Industrial Pipelines
Global – October 27, 2026 -- Even QoS 2's exactly-once delivery covers only one MQTT sender-receiver flow, not the subscriber's database transaction, so an MQTT broker cannot serve as an industrial historian. A broker moves messages between publishers and subscribers. A historian keeps time-indexed records that engineers can query, trend and aggregate later.
Broker retention mechanisms fall short of historical storage
A retained message is only the current message for a topic, and a new one normally replaces the prior state. A persistent session preserves subscriptions and eligible queued messages for an offline client. Session expiry, broker capacity, message expiry and administrative policy can all limit what remains.
Broker persistence protects broker state across restarts. It does not define table schemas, engineering timestamps, multi-year retention, SQL queries, aggregates or audit-ready change history.