Differences in Constraint Checking
Constraint checking in Vector differs from traditional Ingres in the following ways:
• When loading data with COPY, if a constraint violation is detected, the entire dataset is rejected.
• When loading data with COPY, Vector detects foreign key (referential) constraint violations, unlike traditional Ingres.
• Vector does not handle cyclic constraints.
• Because of the
optimistic concurrency control model (see
Transaction Isolation Model) used by Vector, it is possible that a constraint violation is only detected at commit time.