Kafka
3 focused explainers for readers who want the useful answer, a clear example, and a practical next step.
Kafka partition count planning: throughput is only one constraint
Partitions control parallelism, ordering, recovery work, and metadata cost, which makes a single messages-per-second formula.
Kafka consumer lag is not enough: measure processing age too
A consumer can have low offset lag while processing old events, so operations need both queue depth and event-age.
Kafka KRaft migration: a rollback-aware plan for production clusters
Moving Kafka metadata from ZooKeeper to KRaft is an operational migration, not a configuration rename, and each phase needs a stop.