Guarantees on Ordering

For each publisher, on a single topic, AMPS is guaranteed to deliver messages to subscribers in the same order that the messages were published by the original publisher. This guarantee holds true regardless of how many publishers or how many subscribers are connected to AMPS at any one time.

For each instance, AMPS is guaranteed to deliver messages in the order in which the messages were received by the instance, regardless of whether a message is received directly from a publisher or indirectly via replication. The message order for the instance is recorded in the transaction log, and is guaranteed to remain consistent across server restarts.

These guarantees mean that subscribers will not spend unnecessary CPU cycles checking timestamps or other message content to verify which message is the most recent, or reordering messages during playback. This frees up subscriber resources to do more important work.

AMPS preserves an absolute order across topics for a single subscription for all topics except views, queues, and conflated topics. Applications often rely on this behavior to correlate the times at which messages to different topics were processed by AMPS. See Message Ordering for more information.