Ozan

The username in this thread is doing a lot of work and I feel seen.

The part I would emphasise is the halfway-dead state rather than the CPU limit, because that is the bit that actually hurts.

A migration that fails cleanly is fine. A migration that gets killed partway leaves a database in a state that exists in nobody's plan, and if it is not idempotent your recovery options are backup or hand-repair.

I write every backfill to be re-runnable now, even when that costs an extra column.