[Solved] You have this Kafka producer code snippet:producer.send(new ProducerRecord("topic", null, "msg1")); producer.send(new ProducerRecord("topic", null, "msg2"));Why might message order not be preserved? | Kafka

Kafka - Topics and Partitions

You have this Kafka producer code snippet:

producer.send(new ProducerRecord<>("topic", null, "msg1"));
producer.send(new ProducerRecord<>("topic", null, "msg2"));

Why might message order not be preserved?

ABecause the topic has only one partition.

BBecause Kafka always reorders messages regardless of keys.

CBecause messages with null keys can go to different partitions, losing order.

DBecause the producer is synchronous.

Step-by-Step Solution

Solution:

Step 1: Analyze key usage in ProducerRecord
Null keys mean Kafka uses round-robin or default partitioner, sending messages to different partitions.
Step 2: Understand ordering impact
Messages in different partitions have no ordering guarantee, so order may be lost.
Final Answer:
Because messages with null keys can go to different partitions, losing order. -> Option C
Quick Check:
Null key = no partition order guarantee [OK]

Quick Trick: Null keys cause messages to spread partitions, breaking order [OK]

Common Mistakes:

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