\begin{frame}
  \frametitle{Data Independence}

  \begin{goal}{Logical data independence}
    \emph{Logical data independence} is the ability to modify the logical schema without breaking existing applications
      \begin{itemize}
        \item applications access the views, not the logical database 
      \end{itemize}
  \end{goal}
  \medskip
  
  \begin{goal}{Physical data independence}
    \emph{Physical data independence} is the ability to modify the physical schema without changing the logical schema
      \begin{itemize}
        \item e.g. a change in workload might cause the need for
          \begin{itemize}
            \item different indexing structures
            \item different database engine
            \item distributing the database on multiple machines
            \item \ldots
          \end{itemize}
      \end{itemize}
  \end{goal}

\end{frame}