Integration / Apache Pulsar Interview questions
What is a consumer in Pulsar?
A consumer is a client process that subscribes to a topic (via a named subscription) to receive and process published messages, then acknowledges each message once it's been handled.
A consumer's behavior - which messages it sees, and whether other consumers share the load - is determined by the subscription type it uses (Exclusive, Shared, Failover, or Key_Shared).
Unacknowledged messages remain in the subscription's backlog and will be redelivered - immediately on a negative ack, or after a timeout for an unresponsive consumer - so acknowledgment is what actually advances the subscription's read position.
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