I wonder if Datomic’s model has room for something like an “extra-strict” transaction. Such a transaction would operate exactly like an ordinary transaction except that it would also check that no transaction element reads a value or predicate that is modified by a different element. This would be a bit like saying that each element would work like an independent transaction, submitted concurrently, in a more conventional serializable database (with predicate locking!), except that the transaction only commits if all the elements would commit successfully.
This would have some runtime cost and would limit the set of things one could accomplish in a transaction. But it would remove a footgun, and maybe this would be a good tradeoff for some users, especially if it could be disabled on a per-transaction basis.
This would have some runtime cost and would limit the set of things one could accomplish in a transaction. But it would remove a footgun, and maybe this would be a good tradeoff for some users, especially if it could be disabled on a per-transaction basis.