No, we're using a table as a 'queue' in the db. Client are decoupled and if our middleware is offline, it can restart and catch up by draining the table. Transactions over the table ensure the consistency and integrity of the 'queue'. We provide at-least-once semantics to downstream apps, by exploiting transactions in the DB. Actually, we have one sink in the DB itself and we get exactly once semantics for that. The work in under submission with anonymous reviewing, so can't elaborate massively on everything else. Performance numbers are good, though, a sigle server can forward more than 10k ops/sec from the database changelog to a downstream db used for freetext search.