Interactive queries in Kafka - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the main purpose of interactive queries in Kafka Streams?

Interactive queries allow you to directly query the state stores of a Kafka Streams application to get real-time data without needing to go through Kafka topics.

intermediate

How do you access a local state store in Kafka Streams for interactive queries?

You use the KafkaStreams#store() method with the store name and queryable store type to get a handle to the local state store.

beginner

What is a key benefit of using interactive queries instead of querying Kafka topics directly?

Interactive queries provide low-latency, real-time access to aggregated or processed data stored locally, avoiding the overhead of consuming and processing raw Kafka topic data again.

intermediate

What happens if the requested key is not found in the local state store during an interactive query?

If the key is not found locally, you can use Kafka Streams metadata APIs to find which instance has the key and then query that instance remotely.

beginner

Name two types of state stores that can be queried interactively in Kafka Streams.

KeyValueStore and WindowStore are two common types of state stores that support interactive queries.

What method is used to access a local state store for interactive queries in Kafka Streams?

A KafkaStreams#store()

B KafkaConsumer#poll()

C KafkaProducer#send()

D KafkaStreams#start()

KafkaStreams#store() is the method to access local state stores for interactive queries.

Which of the following is NOT a benefit of interactive queries?

A Real-time access to processed data

B Low latency querying

C Directly modifying Kafka topic data

D Avoiding reprocessing raw data

Interactive queries do not allow direct modification of Kafka topic data; they provide read access to local state stores.

If a key is not found in the local state store, what can Kafka Streams do?

A Query the Kafka topic directly

B Use metadata to find the instance that has the key and query it

C Return null immediately

D Restart the Kafka Streams application

Kafka Streams can use metadata APIs to locate the instance holding the key and query it remotely.

Which store type supports windowed data in interactive queries?

A WindowStore

B GlobalStore

C SessionStore

D KeyValueStore

WindowStore supports windowed data and can be queried interactively.

Interactive queries are primarily used in which Kafka component?

A Kafka Connect

B Kafka Producer

C Kafka Consumer

D Kafka Streams

Interactive queries are a feature of Kafka Streams to query local state stores.

Explain what interactive queries are in Kafka Streams and why they are useful.

Think about how you get data directly from your app's memory instead of reading from Kafka topics.

Describe the process Kafka Streams uses when a requested key is not found locally during an interactive query.

Consider how the app finds the right place to get the data if it’s not on the current machine.