Goal Find ROW level BEFORE triggers that check a condition based on other rows, raise an exception but do not return the row if the condition check succeeds, i.e., exception is not raised.
Type Problem detection (Each row in the result could represent a flaw in the design)
Reliability Medium (Medium number of false-positive results)
License MIT License
Fixing Suggestion INSERT and UPDATE triggers should have RETURN NEW in their functions and DELETE triggers should have RETURN OLD in their functions.
Data Source INFORMATION_SCHEMA+system catalog
SQL Query
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,
     p.prosrc AS routine_definition,
     (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, action_timing, event_manipulation, action_orientation, action_condition, routine_name, regexp_replace(routine_definition,'[\r\n]','
','g') AS routine_definition FROM Tr WHERE action_orientation='ROW' AND action_timing='BEFORE' AND routine_definition~* 'IF[[:space:]]+.*[[:space:]]THEN' AND routine_definition~* 'SELECT[[:space:]]+.*[[:space:]]FROM' AND routine_definition~* 'RAISE[[:space:]]+EXCEPTION' AND ((event_manipulation IN ('INSERT','UPDATE') AND routine_definition!~* 'RETURN[[:space:]][^;]*NEW') OR (event_manipulation IN ('DELETE') AND routine_definition!~* 'RETURN[[:space:]][^;]*OLD')) ORDER BY trigger_schema, trigger_table, routine_name;
Collections

This query belongs to the following collections:

NameDescription
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

This query is classified under the following categories:

NameDescription
Triggers and rulesQueries of this category provide information about triggers and rules in a database.

Further reading and related materials:

Reference
https://www.postgresql.org/docs/current/plpgsql-trigger.html