How to connect PostgreSQL with Codeigniter?

As all of us know that postgrest sql is more bigger then mysql so it can store big data and more feature then mysql
one more thing is that postgrest sql are free it is open source

So how to connect postgrest sql with codeigniter??

1 ) Go to our codeigniter project and find config -> database.php

  Config it to:

2) Go to our web server xampp or warmp 

Go to edit on php.ini 

- un comment 

If warning need to add this code in our project