Partition count strategy in Kafka - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to set the number of partitions when creating a Kafka topic.

Kafka

NewTopic topic = new NewTopic("my-topic", [1], (short) 1);

Drag options to blanks, or click blank then click option'

A"3"

BnumPartitions

Cpartitions

D3

Attempts:

3 left

💡 Hint

Common Mistakes

Using a string instead of an integer for partitions.

Using a variable name without declaration.

The number of partitions must be an integer value, like 3, not a string or variable name.

2fill in blank

medium

Complete the code to retrieve the partition count of a Kafka topic using AdminClient.

Kafka

DescribeTopicsResult result = adminClient.describeTopics(Collections.singleton("my-topic"));
Map<String, TopicDescription> descriptions = result.all().get();
int partitionCount = descriptions.get("my-topic").[1]().size();

Drag options to blanks, or click blank then click option'

Apartitions

BgetPartitionCount

CgetPartitions

DpartitionsCount

Attempts:

3 left

💡 Hint

Common Mistakes

Using a method that does not exist like getPartitionCount.

Using a field name instead of a method.

The method getPartitions() returns the list of partitions for the topic.

3fill in blank

hard

Fix the error in the code that sets the partition count dynamically based on a variable.

Kafka

int partitions = 5;
NewTopic topic = new NewTopic("my-topic", [1], (short) 1);

Drag options to blanks, or click blank then click option'

A"partitions"

Bpartitions

Cpartitions.toString()

DInteger.parseInt(partitions)

Attempts:

3 left

💡 Hint

Common Mistakes

Putting the variable name in quotes making it a string.

Trying to parse an int variable as if it were a string.

The constructor expects an int for partitions, so use the variable directly without quotes or conversion.

4fill in blank

hard

Fill both blanks to create a topic with a partition count and replication factor.

Kafka

NewTopic topic = new NewTopic("my-topic", [1], (short) [2]);

Drag options to blanks, or click blank then click option'

A4

B2

C1

D3

Attempts:

3 left

💡 Hint

Common Mistakes

Using replication factor greater than available brokers.

Using zero or negative numbers.

The topic is created with 3 partitions and replication factor 1.

5fill in blank

hard

Fill all three blanks to create a topic and check if the partition count is greater than 3.

Kafka

NewTopic topic = new NewTopic("my-topic", [1], (short) [2]);
int count = topic.[3]();
if (count > 3) {
    System.out.println("Many partitions");
}

Drag options to blanks, or click blank then click option'

A5

B1

CnumPartitions

Dpartitions

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong method name to get partition count.

Using replication factor as partition count.

Create topic with 5 partitions, replication factor 1, and use numPartitions() method to get count.

Practice

1. What does the partition count in a Kafka topic control?

easy

A. The number of parts a topic is divided into for parallel processing

B. The number of messages a topic can hold

C. The size limit of each message in the topic

D. The number of consumers allowed to read the topic

Solution

1. Step 1: Understand Kafka topic structure

   A Kafka topic is divided into partitions to allow parallel processing of messages.

2. Step 2: Identify what partition count controls

   The partition count sets how many parts the topic is split into, enabling multiple consumers to read in parallel.

3. Final Answer:

   The number of parts a topic is divided into for parallel processing -> Option A

4. Quick Check:

   Partition count = number of topic parts [OK]

Hint: Partition count means how many parts a topic has [OK]

Common Mistakes:

• Confusing partition count with message size
• Thinking partition count limits consumer numbers
• Assuming partition count controls message retention

2. Which of the following is the correct way to set the partition count when creating a Kafka topic using the command line?

easy

A. kafka-topics --create --topic myTopic --partitions 3 --bootstrap-server localhost:9092

B. kafka-topics --create --topic myTopic --num-partitions 3 --bootstrap-server localhost:9092

C. kafka-topics --create --topic myTopic --partition-count 3 --bootstrap-server localhost:9092

D. kafka-topics --create --topic myTopic --part 3 --bootstrap-server localhost:9092

Solution

1. Step 1: Recall Kafka topic creation syntax

   The correct flag to set partitions is --partitions.

2. Step 2: Match the correct command option

   kafka-topics --create --topic myTopic --partitions 3 --bootstrap-server localhost:9092 uses --partitions 3, which is the correct syntax.

3. Final Answer:

   kafka-topics --create --topic myTopic --partitions 3 --bootstrap-server localhost:9092 -> Option A

4. Quick Check:

   Partition flag = --partitions [OK]

Hint: Use --partitions to set partition count [OK]

Common Mistakes:

• Using --num-partitions instead of --partitions
• Using --partition-count which is invalid
• Using --part which is invalid

3. Given a Kafka topic with 4 partitions, what will be the partition number for a message with key hash % 4 = 2?

medium

A. Partition 0

B. Partition 1

C. Partition 2

D. Partition 3

Solution

1. Step 1: Understand partition assignment by key hash

   Kafka assigns messages to partitions by taking the key hash modulo the number of partitions.

2. Step 2: Calculate partition number

   Given key hash % 4 = 2, the message goes to partition 2 (zero-based indexing).

3. Final Answer:

   Partition 2 -> Option C

4. Quick Check:

   Key hash % partitions = partition number [OK]

Hint: Partition = key hash modulo partition count [OK]

Common Mistakes:

• Confusing modulo result with partition index
• Assuming partitions start at 1 instead of 0
• Ignoring key hash in partition calculation

4. You tried to create a Kafka topic with 0 partitions using the command: kafka-topics --create --topic test --num-partitions 0 --bootstrap-server localhost:9092. What is the likely issue?

medium

A. Kafka allows 0 partitions, so topic created with no data storage

B. Error because partition count must be at least 1

C. Topic created with default partition count of 1

D. Command ignored the partition count and created topic anyway

Solution

1. Step 1: Understand partition count constraints

   Kafka requires at least one partition per topic; zero is invalid.

2. Step 2: Identify command behavior

   Setting partitions to 0 causes an error because Kafka cannot create a topic without partitions.

3. Final Answer:

   Error because partition count must be at least 1 -> Option B

4. Quick Check:

   Partition count ≥ 1 required [OK]

Hint: Partition count cannot be zero or negative [OK]

Common Mistakes:

• Assuming Kafka defaults to 1 partition silently
• Thinking zero partitions means no data but topic exists
• Ignoring error messages from Kafka CLI

5. You have a Kafka topic with 5 partitions and want to increase parallel processing. Which is the best strategy?

hard

A. Delete the topic and create a new one with 1 partition

B. Decrease the partition count to 3 to reduce complexity

C. Keep partition count at 5 and add more consumers than partitions

D. Increase the partition count to 10 and rebalance consumers

Solution

1. Step 1: Understand effect of partition count on parallelism

   More partitions allow more consumers to read in parallel, increasing throughput.

2. Step 2: Evaluate options for increasing parallel processing

   Increasing partitions to 10 allows better parallelism; rebalance consumers to use new partitions.

3. Final Answer:

   Increase the partition count to 10 and rebalance consumers -> Option D

4. Quick Check:

   More partitions = better parallel processing [OK]

Hint: More partitions mean more parallel consumers [OK]

Common Mistakes:

• Reducing partitions thinking it improves speed
• Adding more consumers than partitions without increasing partitions
• Deleting topic unnecessarily