Definition
Plain language
A database trick that keeps several past versions of a value around at once, so readers and writers don't have to wait on each other.
As stated in the literature
MVCC — a concurrency-control scheme that retains multiple timestamped versions of each datum so reads can be served a consistent snapshot without blocking writes; classical variants treat a version as a single value, which CoAgent extends to an ordered trajectory of operations to handle append-style writes.
Also called: MVCC, multiversion ordering, multiversion
Why it matters: It lets databases serve many readers and writers at once without them blocking each other, keeping systems fast and consistent under heavy use.
For example, while one user is updating a bank balance, another user reading it sees a clean earlier snapshot instead of being forced to wait or seeing half-finished data.
Heard on the show
“Classical multiversion ordering keeps multiple versions, but it treats a version as just a value — it silently assumes every write is an overwrite.”Episode 150 — Don't Kill the Loser: A Different Way to Handle Two AI Agents Colliding