PostgreSQL Triggers: Where They Belong and Where They Don't
Triggers should not host general application logic, but they are essential for enforcing database integrity and consistency. For maintaining redundant data reliably, or preprocessing incoming rows—such as normalizing text to lowercase—a trigger is the correct tool.
While application code can replicate these behaviors, doing so is inherently more fragile. Application-level solutions are prone to errors from missed code paths, and any manual database intervention is likely to break consistency. A trigger, by contrast, provides a hard guarantee that such inconsistencies cannot occur.
As a practical guideline: if the logic is lengthy and complex, keep it out of a trigger. If it deals with straightforward rules that protect the database's consistency, a trigger is the right fit.
