Dead letter queue (DLQ) je red čekanja gdje odlaze poruke koje se ne mogu obraditi ili ispunjavaju određene uvjete (odbijene, istekle, red pun). DLQ-ovi sprječavaju da problematične poruke budu izgubljene ili da blokiraju obradu, omogućujući bolju analizu i rukovanje kasnije.
Što je dead letter queue
DEAD LETTER QUEUE → a queue that receives messages that couldn't be delivered/processed
normally:
→ messages are "dead-lettered" (routed to the DLQ) when they:
- are REJECTED/nacked (consumer can't process them) without requeue
- EXPIRE (message TTL exceeded)
- exceed the queue's MAX LENGTH (overflow)
→ the DLQ collects these for inspection/handling instead of losing them
→ a "holding area" for problematic messages
