Postgresql medium
Which set of commands allows PostgreSQL to function as a low-latency asynchronous signaling or notification bus?
- A COMMIT / ROLLBACK: Used to finalize or abort the current atomic transaction block.
- B LISTEN / NOTIFY: Used to broadcast and receive messages on specific named channels.
- C GRANT / REVOKE: Used to manage the granular permission levels for specific user roles.
- D FETCH / MOVE: Used to reposition a database cursor within a large result set in memory.
Answer: B. LISTEN / NOTIFY: Used to broadcast and receive messages on specific named channels.
Postgres has built-in Pub/Sub. Applications can `LISTEN` for events and be notified immediately (with a string payload) when another process calls `NOTIFY`. This is great for invalidating caches or triggering webhooks.
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