致命错误：调用未定义的函数pg_connect（）

I am trying to connect to my database (remote server) which has PostgreSQL installed in it. My PHP code is trying to connect to the database using pg_connect(), but I get the error saying:- "Fatal error: Call to undefined function pg_connect() in /var/www/website/functions.php on line 82".I am trying to connect to my database (remote s