An isolation level that guarantees the view of data as it stood when a transaction began.
An isolation level that guarantees read consistency by continuing to reference a snapshot taken at the moment the transaction began. It has a counterintuitive weakness called write skew: two transactions reading the same snapshot can each update a different row without noticing the other, and both commit successfully even though the combined result violates an invariant neither transaction could see broken alone.
© 2026 ITBGM