Apache Kafka Kafka Streams

Question 1

What type of library is Kafka Streams?

Accepted Answer

A client-side Java library for stream processing, requiring no separate cluster

Answer

Kafka Streams is a lightweight Java library embedded in your application — it uses Kafka topics as input/output and needs no additional infrastructure.

Question 2

What is a KStream in Kafka Streams?

Accepted Answer

An unbounded sequence of individual key-value records (changelog stream)

Answer

A KStream represents a continuous, unbounded stream of key-value records where each record is an independent event.

Question 3

What is a KTable in Kafka Streams?

Accepted Answer

A changelog stream interpreted as a table where each record is an upsert by key

Answer

A KTable models a mutable table backed by a changelog topic; each new record with an existing key updates (upserts) the current value for that key.

Question 4

Which method is used to materialize a KTable into a queryable local state store?

Accepted Answer

Materialized.as()

Answer

Materialized.as() specifies a named state store backed by RocksDB where the KTable's data is accessible for interactive queries.

Question 5

What is the default state store backend used by Kafka Streams for persistent state?

Accepted Answer

RocksDB

Answer

Kafka Streams uses RocksDB as its default embedded persistent key-value store for local state in aggregations and joins.

Apache Kafka Practice Test

Apache Kafka Practice Test

Apache Kafka Kafka Streams