Recursive rules that directly modify their home table

Query goal:

Do not cause potentially infinite loops. Recursive rules would fire itself over and over again. Although the system is able to detect these after executing a data modification statement it is better to avoid creating these altogether.

Notes about the query:

Rules are specific to PostgreSQL and thus it is not possible to get information about these from the INFORMATION_SCHEMA views. The query does not detect all possible recursions because multiple rules on different tables can also form a cycle. Different schemas could have tables with the same name. Thus, the query has to check that the table identifier is not a multipart identifier that also contains schema name.

Query type:

Problem detection (Each row in the result could represent a flaw in the design)

Query reliability:

High (Few or no false-positive results)

Query license:

MIT License

Fixing suggestion:

Drop the rule.

Data source:

system catalog only

SQL query:

Click on query to copy it

WITH rules AS (SELECT n.nspname AS schemaname,
    c.relname AS tablename,
    r.rulename,
    CASE WHEN ev_type='1' THEN 'SELECT' WHEN ev_type='2' THEN 'UPDATE' WHEN ev_type='3' THEN 'INSERT' ELSE 'DELETE' END AS event,
    pg_get_ruledef(r.oid) AS definition
   FROM pg_rewrite r
     JOIN pg_class c ON c.oid = r.ev_class
     JOIN pg_namespace n ON n.oid = c.relnamespace
     JOIN pg_authid u ON  n.nspowner = u.oid
  WHERE r.rulename <> '_RETURN' AND
(n.nspname = 'public' OR u.rolname <> 'postgres')) 
SELECT schemaname, tablename, rulename, event, definition
FROM rules
WHERE definition ILIKE '% DO %' || event || '%' || tablename || '%'
AND definition NOT ILIKE '% DO %' || event || '%' || '.' || tablename || '%'
ORDER BY schemaname, tablename, rulename, event;

SQL statements for generating SQL statements that help us to fix the problem

SQL query	Description
WITH rules AS (SELECT n.nspname AS schemaname, c.relname AS tablename, r.rulename, CASE WHEN ev_type='1' THEN 'SELECT' WHEN ev_type='2' THEN 'UPDATE' WHEN ev_type='3' THEN 'INSERT' ELSE 'DELETE' END AS event, pg_get_ruledef(r.oid) AS definition FROM pg_rewrite r JOIN pg_class c ON c.oid = r.ev_class JOIN pg_namespace n ON n.oid = c.relnamespace JOIN pg_authid u ON n.nspowner = u.oid WHERE r.rulename <> '_RETURN' AND (n.nspname = 'public' OR u.rolname <> 'postgres')) SELECT format('DROP RULE %1$I ON %2$I.%3$I', rulename, schemaname, tablename) AS statements FROM rules WHERE definition ILIKE '% DO %' \|\| event \|\| '%' \|\| tablename \|\| '%' AND definition NOT ILIKE '% DO %' \|\| event \|\| '%' \|\| '.' \|\| tablename \|\| '%' ORDER BY schemaname, tablename, rulename, event;	Drop the rule.

SQL query

Description

WITH rules AS (SELECT n.nspname AS schemaname,
    c.relname AS tablename,
    r.rulename,
    CASE WHEN ev_type='1' THEN 'SELECT' WHEN ev_type='2' THEN 'UPDATE' WHEN ev_type='3' THEN 'INSERT' ELSE 'DELETE' END AS event,
    pg_get_ruledef(r.oid) AS definition
   FROM pg_rewrite r
     JOIN pg_class c ON c.oid = r.ev_class
     JOIN pg_namespace n ON n.oid = c.relnamespace
     JOIN pg_authid u ON  n.nspowner = u.oid
  WHERE r.rulename <> '_RETURN' AND
(n.nspname = 'public' OR u.rolname <> 'postgres')) 
SELECT format('DROP RULE %1$I ON %2$I.%3$I', rulename, schemaname, tablename) AS statements
FROM rules
WHERE definition ILIKE '% DO %' || event || '%' || tablename || '%'
AND definition NOT ILIKE '% DO %' || event || '%' || '.' || tablename || '%'
ORDER BY schemaname, tablename, rulename, event;

Drop the rule.

Collections where the query belongs to

Collection name	Collection 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 .

Collection name

Collection 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 where the query belongs to

Category name	Category description
Triggers and rules	Queries of this category provide information about triggers and rules in a database.

Category name

Category description

Triggers and rules

Queries of this category provide information about triggers and rules in a database.