list_primary_key.sql

select 
      kcu.table_name, 
      array_agg(kcu.column_name::text order by kcu.ordinal_position asc) as key_column 
  from information_schema.table_constraints tco 
       join information_schema.key_column_usage kcu on kcu.constraint_name = tco.constraint_name 
         and kcu.constraint_schema = tco.constraint_schema 
         and kcu.constraint_name = tco.constraint_name 
where tco.constraint_type = 'PRIMARY KEY' 
group by 1;