Update Dec 2016 : HHVM now fully supports pgsql.
Thanks to failed upgrade of Windows 8->10, I get a fresh install of Windows 10. By fresh install I mean all my installed programs were gone. OK not a big deal, so I installed Ubuntu LTS and fortunately xampp/htdocs directory was untouched (unlike /data of PostgreSQL). So I backed up my projects in htdocs and start to build an HHVM-nginx-Postgre engine on local. Never done it before.
Some nginx’s .conf settings and localhost gave me blank screen.
Ctrl+Shift+I -> Network said that it was error 500 hphp_invoke. Google it, found that I have to check /var/log/hhvm/error.log. I checked and voila! My bad, hhvm does not support pg_connect.