add extra parameter or search paramerter with pagging in codeginiter

In pagination config:
if (count($_GET) > 0) $config['suffix'] = '?' . http_build_query($_GET, '', "&");

Your current $_GET vars will be shown in pagination links. You can replace $_GET by another associative array. This won’t add a query string unless one already exists.

Update: I just saw, if you go back from another pagination number to click on the first(1), CI does not care anymore of your suffix config.

To fix that use $config[‘first_url’].

e.g: $config['first_url'] = $config['base_url'].'?'.http_build_query($_GET);