
A writer changes the present, but a reader is never forced to wait for it.
Every transaction is stamped with the moment of its birth, and shown only the world as it stood then. Old versions do not vanish; they linger as frozen snapshots, immutable and undisturbed.
No one shares a single present, so no one ever blocks anyone else's past.
This is multi-version concurrency control: readers see a consistent past while writers race ahead, and the two never collide.