Topic creation in Kafka - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a Kafka topic?

A Kafka topic is a category or feed name to which records are published. It acts like a folder where messages are stored and organized.

beginner

How do you create a Kafka topic using the command line?

You use the command kafka-topics.sh --create --topic <topic-name> --bootstrap-server <server> --partitions <num> --replication-factor <num> to create a topic.

intermediate

What does the replication factor mean in Kafka topic creation?

Replication factor is the number of copies of the topic's data across different Kafka brokers. It helps with fault tolerance.

intermediate

Why do you specify the number of partitions when creating a Kafka topic?

Partitions allow Kafka to split data into smaller parts for parallel processing and scalability. More partitions mean better throughput.

beginner

Can Kafka topics be created automatically?

Yes, Kafka can auto-create topics when a producer or consumer tries to use a non-existing topic if the broker is configured to allow it.

Which command option is used to create a Kafka topic?

A --delete

B --create

C --list

D --describe

The option '--create' is used with kafka-topics.sh to create a new topic.

What does the replication factor control in a Kafka topic?

A Number of copies of data across brokers

B Number of topic partitions

C Size of each message

D Retention time of messages

Replication factor controls how many copies of the topic data exist on different brokers for fault tolerance.

Why are partitions important in Kafka topics?

A They control message size

B They encrypt messages

C They allow parallel processing and scalability

D They delete old messages

Partitions split data to allow multiple consumers to read in parallel, improving throughput.

What happens if you try to produce to a non-existing topic and auto-creation is enabled?

A Topic is automatically created

B Message is rejected

C Producer crashes

D Message is lost

Kafka can auto-create the topic if configured, so the message is accepted.

Which of these is NOT a parameter when creating a Kafka topic?

A Topic name

B Number of partitions

C Replication factor

D Message format

Message format is not specified during topic creation; it is handled by producers and consumers.

Explain how to create a Kafka topic using the command line and why you need to specify partitions and replication factor.

Think about how Kafka handles data distribution and fault tolerance.

Describe what happens when Kafka auto-creates a topic and when this feature might be useful or risky.

Consider convenience versus control.

Practice

1. What is the main purpose of a topic in Kafka?

easy

A. To compile Java programs

B. To store user login credentials

C. To manage database connections

D. To organize messages like folders organize files

Solution

1. Step 1: Understand Kafka topic role

   A Kafka topic is a category or feed name to which messages are published.

2. Step 2: Compare options with topic function

   Only To organize messages like folders organize files correctly describes topics as organizing messages like folders organize files.

3. Final Answer:

   To organize messages like folders organize files -> Option D

4. Quick Check:

   Topic = Organize messages [OK]

Hint: Topics group messages like folders group files [OK]

Common Mistakes:

• Confusing topics with databases
• Thinking topics store user data
• Mixing topics with program compilation

2. Which command correctly creates a Kafka topic named orders with 3 partitions and replication factor 2?

easy

A. kafka-topics.sh --create --topic orders --partitions 3 --replication-factor 2 --bootstrap-server localhost:9092

B. kafka-create-topic orders 3 2

C. create-topic --name orders --partitions 3 --replicas 2

D. kafka-topics.sh --new --topic orders --partitions=3 --replicas=2

Solution

1. Step 1: Identify correct Kafka topic creation syntax

   The official command uses kafka-topics.sh with --create, --topic, --partitions, --replication-factor, and --bootstrap-server options.

2. Step 2: Match options with correct syntax

   kafka-topics.sh --create --topic orders --partitions 3 --replication-factor 2 --bootstrap-server localhost:9092 matches the correct syntax exactly; others use wrong commands or options.

3. Final Answer:

   kafka-topics.sh --create --topic orders --partitions 3 --replication-factor 2 --bootstrap-server localhost:9092 -> Option A

4. Quick Check:

   Correct syntax = kafka-topics.sh --create --topic orders --partitions 3 --replication-factor 2 --bootstrap-server localhost:9092 [OK]

Hint: Use kafka-topics.sh with --create and proper flags [OK]

Common Mistakes:

• Using wrong command names
• Missing --bootstrap-server option
• Incorrect option names like --replicas

3. What will happen if you run this command?

kafka-topics.sh --create --topic sales --partitions 5 --replication-factor 1 --bootstrap-server localhost:9092

medium

A. Creates a topic named 'sales' with 1 partition and replication factor 5

B. Fails because replication factor cannot be 1

C. Creates a topic named 'sales' with 5 partitions and replication factor 1

D. Fails due to missing zookeeper connection

Solution

1. Step 1: Analyze command parameters

   The command specifies topic 'sales', 5 partitions, replication factor 1, and bootstrap server.

2. Step 2: Understand Kafka topic creation rules

   Replication factor 1 is valid (means no replicas), and partitions set to 5 means 5 partitions created.

3. Final Answer:

   Creates a topic named 'sales' with 5 partitions and replication factor 1 -> Option C

4. Quick Check:

   Partitions=5, Replication=1 [OK]

Hint: Replication factor 1 means no replicas, partitions as given [OK]

Common Mistakes:

• Confusing partitions with replication factor
• Assuming replication factor 1 is invalid
• Expecting zookeeper connection with bootstrap-server

4. You tried to create a topic with this command:

kafka-topics.sh --create --topic logs --partitions two --replication-factor 3 --bootstrap-server localhost:9092

What is the error?

medium

A. Missing --create flag

B. Invalid number for partitions: 'two' should be a number

C. Replication factor cannot be 3

D. Bootstrap server address is incorrect

Solution

1. Step 1: Check partitions parameter

   The partitions option expects a number, but 'two' is a word, causing a syntax error.

2. Step 2: Verify other parameters

   Replication factor 3 and bootstrap server are valid; --create flag is present.

3. Final Answer:

   Invalid number for partitions: 'two' should be a number -> Option B

4. Quick Check:

   Partitions must be numeric [OK]

Hint: Partitions must be numeric, not words [OK]

Common Mistakes:

• Using words instead of numbers for partitions
• Assuming replication factor 3 is invalid
• Forgetting --create flag

5. You want to create a Kafka topic for a critical system that must not lose messages and should handle high load. Which topic creation settings are best?

hard

A. Partitions: 10, Replication factor: 3

B. Partitions: 1, Replication factor: 1

C. Partitions: 5, Replication factor: 1

D. Partitions: 3, Replication factor: 2

Solution

1. Step 1: Understand requirements for critical system

   High load needs many partitions for parallelism; no message loss needs high replication factor.

2. Step 2: Evaluate options

   Partitions: 10, Replication factor: 3 has 10 partitions (high load) and replication factor 3 (high safety). Others have fewer partitions or lower replication.

3. Final Answer:

   Partitions: 10, Replication factor: 3 -> Option A

4. Quick Check:

   High load + safety = many partitions + high replication [OK]

Hint: More partitions + higher replication = speed + safety [OK]

Common Mistakes:

• Choosing low replication for safety
• Choosing few partitions for high load
• Ignoring replication factor importance