What does isolation.level=read_committed do in a Kafka consumer, and when would you enable it?

What does isolation.level=read_committed do in a Kafka consumer, and when would you enable it?

• A. It ensures the consumer only sees committed (EOS) messages; enable when using transactions and EOS.
• B. It makes the consumer see all messages including uncommitted.
• C. It affects producers only.
• D. It disables transactions.

Answer: (A)

The setting on the consumer side controls visibility of transactional writes. When isolation.level is set to read_committed, the consumer will only see messages from transactions that have been committed (the EOS-enabled, exactly-once scenario). Uncommitted or aborted transactional records are hidden, which is essential if your producers are using transactions and you want to guarantee that downstream processing only acts on committed data. This is not a producer setting, and it doesn’t disable transactions; it simply filters what the consumer can observe to ensure consistency. Enabling it is appropriate when you rely on transactional writes and wants to maintain exactly-once processing semantics in your consumer applications.

The setting on the consumer side controls visibility of transactional writes. When isolation.level is set to read_committed, the consumer will only see messages from transactions that have been committed (the EOS-enabled, exactly-once scenario). Uncommitted or aborted transactional records are hidden, which is essential if your producers are using transactions and you want to guarantee that downstream processing only acts on committed data. This is not a producer setting, and it doesn’t disable transactions; it simply filters what the consumer can observe to ensure consistency. Enabling it is appropriate when you rely on transactional writes and wants to maintain exactly-once processing semantics in your consumer applications.