You have a Kafka topic with 4 partitions. Your producer code uses a custom partitioner but messages always go to partition 0. What is the likely issue?

medium📝 Debug Q6 of 15

Kafka - Performance Tuning

AThe partition count must be set to 0 for custom partitioners

BThe topic only has 1 partition despite configuration

CThe producer is not connected to the Kafka cluster

DThe custom partitioner always returns 0 regardless of key

Step-by-Step Solution

Solution:

Step 1: Analyze custom partitioner behavior
If all messages go to partition 0, the partitioner likely returns 0 always.
Step 2: Check other options for plausibility
Topic has 4 partitions, so B is incorrect; producer connection issues cause errors, not fixed partition; D is valid.
Final Answer:
The custom partitioner always returns 0 regardless of key -> Option D
Quick Check:
Partitioner logic controls partition choice [OK]

Quick Trick: Check partitioner return values for correct partition assignment [OK]

Common Mistakes:

MISTAKES

Assuming topic has fewer partitions
Ignoring partitioner logic
Thinking partition count 0 is valid

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More Kafka Quizzes

You have a Kafka topic with 4 partitions. Your producer code uses a custom partitioner but messages always go to partition 0. What is the likely issue?

Step 1: Analyze custom partitioner behavior

Step 2: Check other options for plausibility

Final Answer:

Quick Check:

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