As I understand it, all column updates within a single row and a single update request are atomic.
My question is this, is the validation call made to validate that update also atomic, in the sense that the current values of the row, if checked by the validation call, will not change underneath the update?
You can think of this sort of like a write lock on the row that begins at validation time and ends when the update completes. This is necessary behavior for some synchronization we need to do. (Basically the validity of the update depends on the comaprison of certain values of the current row and the update values.)