This query identifies violations of modular design principles within user-defined domains. It detects CHECK constraints belonging to a domain where the constraint's name incorporates the identifier of a specific base table that utilizes that domain. Since domains are intended as reusable, abstract data types applicable across multiple entities, embedding a specific implementation context (like a table name) into the constraint's identifier creates semantic coupling. This makes the domain confusing to reuse in other contexts. Constraint identifiers should reflect the inherent logic of the domain (e.g., check_email_format), not the object to which it is applied.
Type
Problem detection (Each row in the result could represent a flaw in the design)
SELECT cdu.table_schema, cdu.table_name, t.table_type, cdu.column_name, cc.check_clause, cc.constraint_name, dc.domain_schema, dc.domain_name
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_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 schema_name IS NOT NULL)
AND cc.constraint_name ILIKE '%' || cdu.table_name || '%'
ORDER BY dc.domain_schema, dc.domain_name;
Collections
This query belongs to the following collections:
Name
Description
Find problems automatically
Queries, that results point to problems in the database. Each query in the collection produces an initial assessment. However, a human reviewer has the final say as to whether there is a problem or not .
Categories
This query is classified under the following categories:
Name
Description
CHECK constraints
Queries of this category provide information about CHECK constraints.
Domains
Queries of this category provide information about reusable specifications of column properties.
Further reading and related materials:
Reference
The corresponding code smell in case of cleaning code is "N2: Choose Names at the Appropriate Level of Abstraction". (Robert C. Martin, Clean Code)