Perhaps CHECK should be associated with a domain

Copy SQL

WITH table_checks_on_domain_columns AS (SELECT 
(SELECT nspname FROM pg_namespace WHERE oid=c.relnamespace) AS table_schema,
c.relname as table_name,
a.attname AS column_name,
o.conname,
n.nspname AS domain_schema,
t.typname AS domain_name, 
replace(substring(pg_get_constraintdef(o.oid),7), a.attname, 'VALUE') AS column_check
FROM pg_constraint o INNER JOIN pg_class c ON c.oid = o.conrelid
INNER JOIN pg_attribute a ON a.attrelid = c.oid AND a.attnum = o.conkey[1] AND a.attisdropped = FALSE
INNER JOIN pg_type AS t ON a.atttypid=t.oid AND t.typtype='d'
INNER JOIN pg_namespace AS n ON t.typnamespace=n.oid
WHERE cardinality(o.conkey)=1 AND o.contype = 'c' AND c.relkind = 'r'),
possibly_problematic_checks AS (SELECT domain_schema, domain_name, column_check, Count(DISTINCT table_schema || '.' || table_name || '.' || column_name) AS nr_of_cols,
string_agg(DISTINCT table_schema || '.' || table_name || '.' || column_name,',<br>' ORDER BY table_schema || '.' || table_name || '.' || column_name) AS columns 
FROM table_checks_on_domain_columns
GROUP BY domain_schema, domain_name, column_check
HAVING Count(DISTINCT table_schema || '.' || table_name || '.' || column_name)>1),
column_domain_usage AS (SELECT cdu.domain_schema, cdu.domain_name, cdu.table_schema, cdu.table_name, cdu.column_name, string_agg(cc.check_clause,';' ORDER BY cc.constraint_name) AS domain_checks
FROM ((INFORMATION_SCHEMA.column_domain_usage AS cdu INNER JOIN
INFORMATION_SCHEMA.tables AS t USING (table_schema, table_name)) INNER JOIN INFORMATION_SCHEMA.domain_constraints AS dc
USING (domain_schema, domain_name)) INNER JOIN INFORMATION_SCHEMA.check_constraints AS cc
USING (constraint_catalog, constraint_schema, constraint_name)
WHERE t.table_type='BASE TABLE' AND cc.check_clause NOT LIKE '%IS NOT NULL'  AND 
cdu.table_schema NOT IN (SELECT schema_name
FROM INFORMATION_SCHEMA.schemata
WHERE schema_name<>'public' AND
schema_owner='postgres' AND catalog_name IS NOT NULL AND schema_name IS NOT NULL)
GROUP BY cdu.domain_schema, cdu.domain_name, cdu.table_schema, cdu.table_name, cdu.column_name)
SELECT domain_schema, domain_name, domain_checks, column_check, nr_of_cols, columns
FROM possibly_problematic_checks LEFT JOIN column_domain_usage USING (domain_schema, domain_name)
ORDER BY domain_schema, domain_name;