Reble

Reble is an open SQL engine for your Iceberg lakehouse. Your models are plain SQL files; Reble derives their dependencies, builds the tables into your catalog and bucket, and refreshes exactly what moved — triggered by cron, CI, Airflow, or an agent.

Every data team ends up building the same expensive hack around that job: a copy of the warehouse for testing changes. You refresh it, you queue for it, you hope it still matches prod — and you pay for it twice. The Apache Iceberg table format already has the primitive that makes it unnecessary: a branch ref is metadata-only, so a "copy" of a 5M-row table costs under 10 ms and zero bytes on any compliant catalog. What was missing is the workflow — deciding what a change touches, making its inputs reproducible, showing what it will do to production rows before anyone accepts it.

Reble is that workflow, and it isn't bolted on: scope, pin, run, diff, promote are what the engine does. When you change a model, it branches, re-runs only the blast radius — your edited models plus their downstream closure, derived from the SQL — shows you the exact rows that will change, and fast-forwards production when you accept. There is no merge step, on purpose: promote or discard, never three-way-merge data, because data merges are where correctness goes to die.