Consumer Group
A consumer group is how several consumers split one topic between them. Within a group each partition is assigned to exactly one consumer, so adding consumers raises throughput — until you pass the partition count, at which point the extras sit idle. Each consumer commits offsets for the partitions it owns, and a different group reads the same data on its own independent schedule.
01 Concept at a Glance
Interactive Step-by-StepRecords are already sitting in three partitions. Now for who reads that log, and how they split it.
02 Understand It Simply
For EveryoneLike staff dividing up warehouse aisles. One person per aisle means no collisions; more people than aisles means someone has nothing to do. A different team can walk the same aisles at their own pace without disturbing the first.
Inside a group, partitions are assigned exclusively, which makes the partition count the ceiling on parallelism.
Each consumer commits the offset it has processed, so restarting resumes from there.
When a consumer joins or leaves, a rebalance recalculates the assignment — and consumption pauses briefly while it happens.
Groups with different IDs never interfere; each reads the same log at its own offsets.
- –Matching consumer count to partition count
- –scaling out throughput
- –choosing an offset-commit strategy (at-least-once vs at-most-once)
- –and fanning the same data out to multiple uses
03 Frequently Asked Questions
FAQWhat is Consumer Group?+
A consumer group is how several consumers split one topic between them. Within a group each partition is assigned to exactly one consumer, so adding consumers raises throughput — until you pass the partition count, at which point the extras sit idle. Each consumer commits offsets for the partitions it owns, and a different group reads the same data on its own independent schedule.
Where is Consumer Group used?+
Matching consumer count to partition count, scaling out throughput, choosing an offset-commit strategy (at-least-once vs at-most-once), and fanning the same data out to multiple uses.
What's a simple analogy for Consumer Group?+
Like staff dividing up warehouse aisles. One person per aisle means no collisions; more people than aisles means someone has nothing to do. A different team can walk the same aisles at their own pace without disturbing the first.