Exactly-once stream processing in Kafka - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does exactly-once stream processing mean in Kafka?

It means each message is processed only one time, no duplicates or missed messages, even if failures happen.

intermediate

What Kafka feature helps achieve exactly-once processing?

Kafka uses transactions to group writes and commits atomically, ensuring messages are processed exactly once.

beginner

Why is idempotence important for exactly-once processing?

Idempotence means repeating an action has the same effect as doing it once, preventing duplicates in failures.

intermediate

How does Kafka Streams API support exactly-once semantics?

Kafka Streams uses transactions and state stores to commit results atomically, avoiding duplicates on restarts.

beginner

What is the role of producer idempotence in Kafka exactly-once processing?

Producer idempotence ensures that resending the same message does not create duplicates in Kafka topics.

Which Kafka feature is essential for exactly-once processing?

A Transactions

B Consumer groups

C Partitions

D Replication

Transactions allow grouping of writes and commits atomically, enabling exactly-once processing.

What does idempotence prevent in Kafka producers?

A Slow consumers

B Message loss

C Duplicate messages

D Partition rebalancing

Idempotence prevents duplicate messages when producers retry sending.

Exactly-once processing guarantees that messages are:

A Processed twice

B Processed at most once

C Processed at least once

D Processed exactly once

Exactly-once means each message is processed one and only one time.

Kafka Streams achieves exactly-once semantics by:

A Using only consumer groups

B Using transactions and state stores

C Disabling replication

D Using manual offset commits

Transactions and state stores allow atomic commits and fault tolerance.

What happens if a Kafka producer is not idempotent and retries sending a message?

A Duplicate messages may appear

B Partition rebalances

C Consumer crashes

D Message is lost

Without idempotence, retries can cause duplicate messages.

Explain how Kafka achieves exactly-once stream processing.

Think about how Kafka groups writes and commits to avoid duplicates.

Why is idempotence important for Kafka producers in exactly-once processing?

Consider what happens when a message is sent multiple times due to failure.