Takahiro Noda <noda(dot)takahiro(dot)47m(at)st(dot)kyoto-u(dot)ac(dot)jp> writes:
> I'm new to PostgreSQL and having been learning SQL. I'm uncertain
> about the exact timing at which CHECK constraints are checked.
They're checked at the instant that a row is inserted or updated.
If you really need a deferred check, you'll need to build it yourself
using an AFTER ROW trigger.
regards, tom lane