I was about to post that a quick grep of CockroachDB source turned up no references to postgres, libpq or anything obvious to back that up that claim but then I noticed my workspace was out of date, so I after a git pull/git grep I now see that you are correct. Commits to add postgres-compatible parsing and wire protocol appear to have landed late last year. Why wasn't I informed! So thank you for this - time for me to take another look at it.