9 Duality View Directives
Directives allow customers to provide supplemental logic for JSON relational Duality Views and their underlying tables, in a declarative manner.
Applications that use duality views often need to extend basic document operations (query, insert, update, delete) with additional logic, such as enforcing business rules beyond what table constraints can express.
A common approach today is to implement this logic in application code or in database triggers. Directives provide a declarative framework for attaching deterministic, transactional supplemental logic to duality view operations. Except where noted for planned features, directive processing is intended to complete within the same database transaction that invokes it.