Query goal: | Find all referential paths (chains of of parent-child tables that are associated through foreign key constraints) where all foreign key constraints have ON DELETE CASCADE compensating actions. Be careful with too long chains. |
Notes about the query: | The query finds transitive closure of tables. In other words it finds all possible paths between tables where it is possible to reach from one table to another based on parent-child relationships. The query assumes that these relationships have been enforced in the database by declaring foreign key (referential) constraints. The path should be read from right to left, i.e., parent table is at right and its child table is at left. |
Query type: | General (Overview of some aspect of the database.) |
Query license: | MIT License |
Data source: | system catalog only |
SQL query: | Click on query to copy it
WITH RECURSIVE transitive_closure AS ( WITH foo AS (SELECT o.conrelid AS child, nl.nspname AS child_table_schema, cl.relname AS child_table, o.confrelid AS parent, nf.nspname AS parent_table_schema, cf.relname AS parent_table FROM pg_constraint AS o INNER JOIN pg_class AS cl ON o.conrelid=cl.oid INNER JOIN pg_namespace AS nl ON cl.relnamespace=nl.oid INNER JOIN pg_class AS cf ON o.confrelid=cf.oid INNER JOIN pg_namespace AS nf ON cf.relnamespace=nf.oid WHERE o.contype='f' AND o.confdeltype='c') SELECT child, parent, child_table_schema, child_table, parent_table_schema, parent_table, 1 AS depth, child || '.' || parent || '.' AS path_string, child_table_schema || '.' || child_table || '/' || parent_table_schema || '.' || parent_table || '/' AS path_string_long FROM foo UNION ALL SELECT tc.child, e.parent, tc.child_table_schema, tc.child_table, e.parent_table_schema, e.parent_table, tc.depth + 1, tc.path_string || e.parent || '.' AS path_string, tc.path_string_long || e.parent_table_schema|| '.' || e.parent_table || '/' AS path_string_long FROM foo AS e INNER JOIN transitive_closure AS tc ON e.child = tc.parent WHERE tc.path_string NOT LIKE '%' || e.parent || '.%') SELECT parent_table_schema, parent_table, child_table_schema, child_table, depth, rtrim(path_string_long,'.') AS path FROM transitive_closure ORDER BY depth DESC, parent_table_schema, parent_table, child_table_schema, child_table; |
Collection name | Collection description |
---|---|
Find problems by overview | Queries that results point to different aspects of database that might have problems. A human reviewer has to decide based on the results as to whether there are problems or not . |
Category name | Category description |
---|---|
Comfortability of data management | Queries of this category provide information about the means that have been used to make the use or management of database more comfortable and thus, more efficient. |
Compensating actions | Queries of this category provide information about compensating actions of foreign key constraints. |
Relationships between tables | Queries of this category provide information about how database tables are connected to each other and whether such connections have been explicitly defined and whether it has been done correctly. |