I now realize I didn't answer how we check uniqueness. We just do a query like any other normal point query, using a serializable transaction, and if we pass t

I now realize I didn't answer how we check uniqueness. We just do a query like any other normal point query, using a serializable transaction, and if we pass the check, then we do the insert with the same transaction (which took a row lock when we did the query because it was serializable, so nothing could have violated the uniqueness between the query and the insert).