big SQL query 

I recently upgraded my Mastodon instance to Debian Buster, so I now have both pgsql 9.6 and 11 installed. (Currently, Mastodon still uses 9.6.)
Which one should I use (and why)?

To all instance admins: you should suspend the instance, it advertises itself as leaking private messages.

(CW n-word on that link and the image)

Octodon is an actively-moderated mostly French-speaking Mastodon instance. est une instance Mastodon principalement francophone et avec une modération active.