It's on their list of approved extensions https://postgres.heroku.com/blog/past/2012/8/2/announcing_support_for_17_new_postgres_extensions_including_dblink/ htt

It's on their list of approved extensions https://postgres.heroku.com/blog/past/2012/8/2/announcing_support_for_17_new_postgres_extensions_including_dblink/ https://postgres.heroku.com/blog/past/2012/8/2/announcing_su... You should be able to say: CREATE EXTENSION ltree; In the database you want it in.