I couldn't find any discussion on this, but the request is quite straightforward. Implement a LIMIT on DELETE statements like SELECT statements.
So you could write:
DELETE FROM massive_table WHERE id < 40000000 LIMIT 10000;
This would allow deletions in smaller batches rather than waiting potentially hours for the server to mark all those rows as deleted and commit it as one massive transaction.
... although I suspect there will be reasons against this.
