Event Hubs: Partitions, Consumer Groups, and Capture

The previous lesson introduced the architecture of Azure Event Hubs. This lesson goes deeper into three critical areas: how partitions affect throughput and ordering, how consumer groups enable independent processing, and how Event Hubs Capture provides automatic archival to Azure Storage. Mastering these concepts is essential for building efficient, scalable streaming pipelines.

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Deep Dive: Partitions

Partitions are the core scalability mechanism in Event Hubs. Every event published to an event hub is appended to exactly one partition.

Partition Count

The number of partitions is set when you create the event hub and cannot be changed after creation (on Standard and Basic tiers). On Premium and Dedicated tiers, partition count can be increased but not decreased.

Rules of thumb for choosing partition count:

• Minimum: Equal to the expected number of parallel consumers
• Maximum: Don't over-partition — more partitions mean more connections and higher cost
• Start with 4–8 partitions for most workloads; scale up if needed

Partition Assignment

Events are assigned to partitions in one of three ways: