You can either be sure it happened, or you have the mechanism to run it again. At gypsum.io, there's a lovely diagram of the relationship among all of the consistency and isolation levels. Every anomaly that is prohibited by serializable is also prohibited by read committed. For those watching on the live stream, we've got a tree diagram up that shows all of the isolation levels,. All of the consistency levels that are commonly used, and how they relate to each other.