As you can see, I have data in my_table that violates the check constraint.
# select * from my_table;
name
──────
test
(1 row)
# \d+ my_table
Table "public.my_table"
Column │ Type │ Modifiers │ Storage │ Stats target │ Description
────────┼───────────┼───────────┼──────────┼──────────────┼─────────────
name │ my_domain │ │ extended │ │
Has OIDs: no
# \dD my_domain
List of domains
Schema │ Name │ Type │ Modifier │ Check
────────┼───────────┼──────┼──────────┼───────────────────────────
public │ my_domain │ text │ │ CHECK (length(VALUE) > 5)
(1 row)