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PostgreSQL transport #266
Description
A transport that needs only Postgres, a database-as-queue approach similar to pg-boss in Node. This lowers the barrier to entry: users can start with the database they already have, get the outbox in the same transaction for free, and move to a broker later.
- Queue tables with
SELECT ... FOR UPDATE SKIP LOCKED, andLISTEN/NOTIFYfor low latency. - Pub/sub via a subscription table.
- Native delayed delivery.
- Pass the
@node-ts/bus-testconformance suite.
Activity
npm create bus-apptemplates #269examples/with docker compose #252adenhertog commentedon Oct 7, 2026
Accepted design (maintainer, 2026-10-07)
PostgresTransport, exported from@node-ts/bus-postgres.transport_messages(keyed by queue),transport_queues,transport_subscriptions,transport_dead_letters.provision()writes the queue row and a subscription row per handled message (and custom-handler topic). It never deletes any.sendandpublishboth fan out with one insert per subscriber, in one statement.sendToAddressinserts into the target queue.for update skip lockedclaim setsvisible_at = now() + visibilityTimeout(default 30 s, configurable, no heartbeat) and a new lease token. A crashed process's message comes back when its lease ends.failedAttemptsis deliveries − 1, like SQS.LISTEN/NOTIFYon a dedicated connection, with a 1 s poll as the fallback.listen: falsefor PgBouncer in transaction mode.returnMessagesetsvisible_at.failmoves the row totransport_dead_letterswith thebus-failureheader. Redrive and purge are documented as SQL.withOutbox()transaction) is a follow-up: postgres transport: exactly-once by enlisting the transport in the outbox transaction #343.provision()creates,initialize()only checks, and the plan has SQL grants for the runtime role.transportTests,outboxTestsandinboxTestsrun against it.