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

A distributed processing engine like Apache Flink

Answer

A REST API layer on top of Kafka

Answer

A separate server component bundled with Kafka

Question 2

What is a KStream in Kafka Streams?

Accepted Answer

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

Answer

A materialized table of the latest value per key

Answer

A windowed aggregation result

Answer

A batch of compressed messages

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 static lookup table loaded from a file

Answer

A batched write buffer

Answer

An in-memory cache of recent messages

Question 4

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

Accepted Answer

Materialized.as()

Answer

toStream()

Answer

groupByKey()

Answer

through()

Question 5

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

Accepted Answer

RocksDB

Answer

LevelDB

Answer

H2 in-process database

Answer

Apache Cassandra

Question 6

What does a 'stream-table join' in Kafka Streams do?

Accepted Answer

Enriches each stream record with the current table value for the matching key

Answer

Merges two streams by timestamp

Answer

Aggregates stream records into table format

Answer

Joins two tables producing a new table