Recursive comments in PostgreSQL

recursive_comments.sql

with recursive co (id, parent_id, body) as
    (select c.id, c.parent_id, c.body
       from comments c
      where c.id = 1
      union all
     select c.id, c.parent_id, c.body
       from co
       join comments c
         on c.parent_id = co.id)
select * from co;