Is it sufficient to perform only ablution, or is a full ritual bath required after the emission of prostatic fluid during sleep?

You must perform ghusl if you are certain that the discharge is semen. However, if you are certain that it is madhy (pre-seminal fluid), then cleanse whatever it has touched, wash your penis, and perform ablution (wudu). If you are in doubt, you should rely on the surrounding circumstances (qara'in); you act upon what the circumstances indicate. If there are no such circumstances, then according to the Shafi'is, you have the choice to consider it either. The Hanbalis are of the view that if it is confirmed to be semen, one must perform ghusl. If it is confirmed to be other than semen, one only cleanses what it has touched. If the matter is ambiguous and preceded by sleep, one cleanses what it has touched, as it is more likely to be madhy. If it was not preceded by sleep, one must perform ghusl, ablution, and cleanse what it has touched.