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 message queue and why would you use one?
A message queue lets one service drop a message and move on, while another service picks it up and processes it later. It decouples services, absorbs traffic spikes, makes slow work asynchronous and retries failures. Examples are RabbitMQ, Amazon SQS and Kafka (a log-based alternative).
IntermediateIn-depth4 min read - How does Kafka keep messages in order, and what role do partitions play?
Kafka guarantees order only within a single partition. Messages with the same key go to the same partition, so ordering holds per key. More partitions give more parallelism but no global order.
IntermediateQuick answer1 min read