I use cookie based sessions, and they work for normal interaction with our site. However, when Googlebot comes crawling out PHP framework, Yii, needs to append ?PHPSESSID to each URL, which doesn't look that good in SERP.

Any ways to suppress this behavior?

PS. I tried to utilize ini_set('session.use_only_cookies', '1');, but it does not work.

PPS. To get an impression of the SERP, they look like this:

• http://www.google.com/search?q=site:wwwdup.uni-leipzig.de+inurl:jobportal