Hello, I’m preparing for the CCDAK exam and got stuck on one of the practice questions. So,

There are two consumers C1 and C2 belonging to the same group G subscribed to topics T1 and T2. Each of the topics has 3 partitions. How will the partitions be assigned to consumers with Partition Assigner being Round Robin Assigner?

A) C1 will be assigned partitions 0 and 2 from T1 and partition 1 from T2. C2 will have partition 1 from T1 and partitions 0 and 2 from T2.

B) Two consumers cannot read from two topics at the same time

C) C1 will be assigned partitions 0 and 1 from T1 and T2, C2 will be assigned partition 2 from T1 and T2.

D) All consumers will read from all partitions

Could someone please explain which one is the correct answer and why?

Hello @jameswilson, I recently passed the exam. This practice question is quite similar to one of the sample exam questions that I got from study4exam for my exam preparation. The Round Robin Partitioner assignment strategy assigns partitions to consumers in a round-robin manner, ensuring an even distribution of partitions across consumers.

As per the given scenario, there are 2 consumers (C1, C2) in the same consumer group (G). They are subscribed to two topics (T1, T2). Each topic has 3 partitions, so there are a total of 6 partitions to assign (T1: p0, p1, p2; T2: p0, p1, p2). The Round Robin Assignment is:

C1 gets T1-p0

C2 gets T1-p1

C1 gets T1-p2

C2 gets T2-p0

C1 gets T2-p1

C2 gets T2-p2

So the distribution would be:

C1: T1-p0, T1-p2, T2-p1

C2: T1-p1, T2-p0, T2-p2

All of this matches the description in option A making it the correct option.

The other options are incorrect because:

B is incorrect because two consumers can indeed read from multiple topics at the same time.

C is incorrect because the Round Robin Assigner doesn’t group partitions by topic.

D is incorrect because each partition can only be assigned to one consumer within the same group.