Understanding ClickHouse's OPTIMIZE TABLE ... FINAL: Usage, Pitfalls, and Merge Mechanics

If you manage a ClickHouse cluster in production, you may have hit duplicate rows or the "too many parts" error. A search result, an older blog post, or a forum thread probably pointed you to OPTIMIZE TABLE ... FINAL. You ran it, the immediate symptom vanished, and you scheduled it in a cron job. We