Interview Q&A / System Design
System Design interview questions
Caching, scaling, databases and classic design problems for beginners.
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- What is a dead letter queue and when do you use one?
A dead letter queue holds messages that failed processing after the allowed retries. It stops one bad message from blocking the queue forever and keeps the message for inspection and later reprocessing.
BeginnerQuick answer1 min read - What is the difference between a message queue and publish-subscribe?
In a queue each message is processed by exactly one consumer from a group, which shares the work. In pub-sub each message is delivered to every subscriber, so many services can react to the same event.
BeginnerQuick answer1 min read