Codessentials

Having unindexed foreign keys can cause multiple problems.

Here you find a query to identify foreign keys not having a proper foreign key:

SELECT * FROM (  
    SELECT c.table_name, cc.column_name, cc.position column_position  
    FROM   user_constraints c, user_cons_columns cc  
    WHERE  c.constraint_name = cc.constraint_name  
    AND    c.constraint_type = 'R'  
    MINUS  
    SELECT i.table_name, ic.column_name, ic.column_position  
    FROM   user_indexes i, user_ind_columns ic  
    WHERE  i.index_name = ic.index_name  
    )  
ORDER BY table_name, column_position;