text: -- This file should undo anything in `up.sql`
  
  ALTER TABLE posts DROP CONSTRAINT posts_pkey;
  ALTER TABLE posts ADD PRIMARY KEY (id);
  ALTER TABLE comments ADD FOREIGN KEY (post) REFERENCES posts(id) ON UPDATE CASCADE ON DELETE CASCADE;
  ALTER TABLE posts DROP COLUMN version_start;
  ALTER TABLE posts DROP COLUMN version_end;
  
  DROP FUNCTION posts_at_version;
  