Why are partitions needed in Kafka and how do they work?

Partitions in Kafka are needed for scaling and improving the performance of the messaging system. A Kafka topic is divided into several partitions — these are separate logical segments where messages are written.

How it works:

• Each partition is stored on a single broker and represents an ordered, immutable log of messages.
• Parallel processing: different partitions can be processed by different consumers simultaneously, increasing throughput.
• Scalability: partitions can be added to distribute load across multiple brokers.
• Message order is guaranteed within a single partition, but not across different partitions.

Thus, partitions allow Kafka to be scaled efficiently, providing load balancing and parallel data processing.