That still doesn't completely answer the question how it avoids race conditions and the likes without locking. Assume I'm executing multiple long-running transa

That still doesn't completely answer the question how it avoids race conditions and the likes without locking. Assume I'm executing multiple long-running transactions, each hitting and modifying a lot (millions) of different objects. How are race conditions avoided in this case ? One engine that distributes and coordinates work plans for the other engines sounds nice, but does this essentially mean that only one of these transactions is able to run at the same time, even when they could be running concurrently when using locking?