Whatever topic has been discussed on this blog is my own finding and views, not necessary match with others. I strongly recommend you to do a test before you implement the piece of advice given at my blog.
We have observed a strange slave process, 'pz99' on our RAC databases for every connection to the database and we were wondering what type of processes are they. Thank god our doubt was cleared without much hassles. According to ML Doc :734139.1 'From Oracle 10g onwards you will find on every node slave processes like pz99. This are the processes that query the gv$ views'