Techniques are disclosed for serializing assertion-triggering transactions by locking special purpose resources (i.e. other than rows or tables), which enables a high level of concurrency for these transactions while at the same time ensuring correctness of the SQL assertion validation code. The techniques involve creating objects referred to therein as “Assertion-Locking Memory-Objects” or “ALMOs”. The database server causes each assertion-triggering transaction to obtain locks on one or more ALMOs prior to determining whether the changes made by assertion-triggering transaction violates the assertion. Because locks on the ALMOs are finer than the table locks, fewer transactions are blocked by ALMO locks.