Hiding private records from search results (Thinking Sphinx)

If your app has an is_private boolean attribute on certain models, and
records where Model.is_private? == true should be ignored from search
results, would you define these records to be ignored in the search
indices (not that I know how to do this with Thinking Sphinx) or would
you use conditions in the search (?);

User.search “Australia”, :conditions => {:is_private => false}