The list of all the queries

Trigger is used to enforce referential integrity

Query goal: Find tables where user-defined (non-system) triggers are used to implement referential integrity. In addition to table name show the triggers and the number of triggers.
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 triggers and declare instead foreign key constraints.
Data source: INFORMATION_SCHEMA+system catalog
SQL query: Click on query to copy it

WITH Tr AS (SELECT
    n.nspname AS trigger_schema,
    t.tgname AS trigger_name,
    em.text AS event_manipulation,        
    c.relname AS trigger_table, 
    np.nspname AS routine_schema,
    p.proname AS routine_name,   
	EXISTS (SELECT * FROM pg_constraint AS o WHERE t.tgconstraint=o.oid AND o.contype ='t') AS is_constraint_trigger,
     (SELECT DISTINCT action_condition FROM INFORMATION_SCHEMA.triggers AS it WHERE it.trigger_schema=n.nspname AND it.event_object_table=c.relname AND it.trigger_name=t.tgname) AS action_condition,    
        CASE t.tgtype::integer & 1
            WHEN 1 THEN 'ROW'
            ELSE 'STATEMENT'
        END AS action_orientation,
        CASE t.tgtype::integer & 66
            WHEN 2 THEN 'BEFORE'
            WHEN 64 THEN 'INSTEAD OF'
            ELSE 'AFTER'
        END AS action_timing	
   FROM pg_namespace n,
    pg_class c,
    pg_trigger t,
    pg_proc p,
    pg_namespace np,
    ( VALUES (4,'INSERT'), (8,'DELETE'), (16,'UPDATE'), (32,'TRUNCATE')) em(num, text)
  WHERE n.oid = c.relnamespace 
  AND c.oid = t.tgrelid 
  AND t.tgfoid=p.oid
  AND p.pronamespace=np.oid
  AND (t.tgtype::integer & em.num) <> 0 
  AND NOT t.tgisinternal 
  AND NOT pg_is_other_temp_schema(n.oid))
SELECT trigger_schema, trigger_table, 
string_agg(trigger_name || CASE WHEN is_constraint_trigger=TRUE THEN '(constraint trigger)' ELSE '' END
|| ' ' || action_timing || ' ' || event_manipulation || ' ' || 'FOR EACH ' || action_orientation || ' EXECUTE ' || routine_name, ',<br>' ORDER BY trigger_name) AS triggers,
Count(*) AS number_of_triggers
FROM Tr
WHERE routine_name~ '^RI_FKey'
GROUP BY trigger_schema, trigger_table
ORDER BY trigger_schema, trigger_table;

Collections where the query belongs to

Collection nameCollection description
Find problems about integrity constraintsA selection of queries that return information about the state of integrity constraints in the datadabase. Contains all the types of queries - problem detection, software measure, and general overview
Find problems automaticallyQueries, 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 nameCategory description
Relationships between tablesQueries 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.
Triggers and rulesQueries of this category provide information about triggers and rules in a database.

Reference materials for further reading

Reference
https://wiki.postgresql.org/wiki/Referential_Integrity_Tutorial_%26_Hacking_the_Referential_Integrity_tables

The list of all the queries