athlete_college_bookmark.rb

belongs_to :athlete

# before we create this new bookmark, we did not need to query SQL for athlete, now we do because of this new mixpanel.
#   Let's assume a query lookup on athlete is 100ms.  So now we have 110ms, which is more than 10x the response time.
def before_create
  Mixpanel.track('some_event', {distinct_id: athlete.r_email})
end

some_controller.rb

# we didn't have to do any queries. Let's say this finishes in 10ms
def bookmark
  AthleteCollegeBookmark.create({
    athlete_id: params[:athlete_id],
    college_id: params[:college_id]
  })
end