Integration / Apache Pulsar Interview questions
What is a non-persistent topic in Pulsar?
A non-persistent topic keeps messages only in broker memory and never writes them to BookKeeper, trading durability for lower publish latency and no storage overhead.
If a broker restarts or crashes, any messages still in flight on a non-persistent topic are lost, and there's no backlog to replay - consumers only see messages published while they're actively connected.
It suits use cases where occasionally losing a message is acceptable in exchange for speed, such as ephemeral real-time metrics or best-effort notifications, not data that must be durably retained.
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