Obtenir la liste des tables qui seraient tronquées par une cascade

Question

Existe-t-il un moyen d'obtenir une liste de tables qui serait également tronquée par un TRUNCATE CASCADE dans postgres?

Ainsi, par exemple, en supposant que nous avons trois tables:

a 
b (depends on a) 
c (depends on b) 

TRUNCATE a CASCADE; tronquait aussi b et c. Comment pourrions-nous vérifier cela à l'avance?

Answer 1

Avec l'aide de this réponse que vous pouvez obtenir le nom de la table étrangère par cette requête

SELECT tc.constraint_name 
     ,tc.table_name 
     ,kcu.column_name 
     ,ccu.table_name AS foreign_table_name 
     ,ccu.column_name AS foreign_column_name 
FROM 
    information_schema.table_constraints AS tc 
    JOIN information_schema.key_column_usage AS kcu 
     ON tc.constraint_name = kcu.constraint_name 
    JOIN information_schema.constraint_column_usage AS ccu 
     ON ccu.constraint_name = tc.constraint_name 
WHERE constraint_type = 'FOREIGN KEY' AND ccu.table_name = 'a' 

---

OU

Créer une vue avec une autre requête

CREATE VIEW vdepend_table 
AS 
SELECT s1.constraint_name 
    ,s1.table_name 
    ,s1.column_name 
    ,s1.ordinal_position 
    ,s2.table_name_ref 
    ,s2.column_name_ref 
    ,s2.ordinal_position_ref 
FROM (
    SELECT key_column_usage.constraint_name 
     ,key_column_usage.table_name 
     ,key_column_usage.column_name 
     ,columns.ordinal_position 
    FROM information_schema.key_column_usage 
    JOIN information_schema.columns USING (
      table_name 
      ,column_name 
      ) 
    ) s1 
JOIN (
    SELECT constraint_column_usage.constraint_name 
     ,constraint_column_usage.table_name AS table_name_ref 
     ,constraint_column_usage.column_name AS column_name_ref 
     ,cols_ref.ordinal_position AS ordinal_position_ref 
    FROM information_schema.constraint_column_usage 
    JOIN information_schema.columns cols_ref ON cols_ref.table_name::TEXT = constraint_column_usage.table_name::TEXT 
     AND cols_ref.column_name::TEXT = constraint_column_usage.column_name::TEXT 
    ) s2 ON s1.constraint_name::TEXT = s2.constraint_name::TEXT 
    AND NOT s1.table_name::TEXT = s2.table_name_ref::TEXT; 

utilisation:

select table_name from vdepend_table where table_name_ref='a'