> Running it directly lead to the same result, out of memory.

Is it really the delete operation that causes OOM? That’d be rather
unusual, so feel free to give me more details.

If it’s the subsequent insert that causes the troubles, could you
possibly give us some details on the size of the database after the
optimize call? Did you try to fully optimize the database (…using the
ALL flag or db:optimize($db, true())…)?