kafka.topic.messages_in.rate

Lambda limits MaximumPollers to the number of Kafka topic partitions to maintain ordered processing within partitions. When a topic has few partitions relative to message volume, Lambda cannot scale event pollers sufficiently, creating a throughput ceiling regardless of provisioned capacity.

When CockroachDB changefeeds emit to Kafka and the high_water_timestamp lag increases significantly, it indicates the Kafka sink cannot keep up with database changes. This creates backpressure where database CDC events queue up, potentially causing CockroachDB performance degradation.