it is save use $this->db->insert_id() ?

[eluser]atoleon[/eluser]
I need to insert a new item in my database, but i need to get the id of this item inmediatelly.
I have seen the $this->db->insert_id() function, but i dont know if is it save use it.
what would happen if userA insert an item and before execute the insert_id() funcion, an userB insert another item. It is possible if there are a lot of users writing at the same time.

thank you