This query returns tables which are not referenced by any foreign key.

See also:

• Tables that are not referenced by the foreign keys
• Loner Tables - tables without relationships

Query

select '>- no FKs' as foreign_keys,
       tab.table_schema,
       tab.table_name
       from information_schema.tables tab
where tab.table_schema not in ('information_schema', 'pg_catalog') 
      and tab.table_type ='BASE TABLE'
      and tab.table_schema || '.' || tab.table_name not in
          (select distinct tco.table_schema || '.' ||tco.table_name
           from information_schema.referential_constraints rco
           join information_schema.table_constraints tco 
                on rco.unique_constraint_name = tco.constraint_name
                and rco.unique_constraint_schema = tco.table_schema)
order by tab.table_schema,
         tab.table_name;

Columns

• foreign_keys - symbol indicating lack of FK references
• table_schema - name of the schema
• table_name - name of the table

Rows

• One row represents one table
• Scope of rows: all tables in a database that are not referenced by the foreign keys
• Ordered by table schema and table name

Sample results

Tables not referenced by foreign keys in sample pagila database.