Glossary

Kafka partition

A Kafka partition is the fundamental unit of parallelism and ordering within a topic. Each partition is an ordered, append-only log of messages. Producers write to partitions (by message key hash or round-robin for null keys). Consumers in a group each own one or more partitions exclusively, so partition count caps consumer group parallelism. Partitions are replicated across brokers according to the replication factor for durability.

Formula: Max parallel consumers per group ≤ partition count per subscribed topic.

Last updated: March 2026