I am writing with regards to some wrong results I keep on receiving when using check_constraints view from information_schema:
(1) First, it shows constraints grouped by name, regardless of the relation used: when having two constraints with the same name in different tables, it shows both in both tables, regardless of their belonging;
You cannot use the standard information_schema.check_constraints in your database because you have not conformed to the standard when naming your constraints. Either ensure unique names for all constraints (in a schema) or use pg_catalog.
(2) Second, it also lists NOT NULL constraints, even though they are not created as check constraints.
That is has special syntax for its creation doesn't mean it isn't functionally a check constraint...so on its face this seems OK.
