\begin{frame} \frametitle{Splitting Relations: Lossless Splits} \vspace{-.5ex} \begin{goal}{} Lossless split guarantees that the schema after splitting can represent all DB states that were possible before. \end{goal} \begin{itemize} \item we can translate states from the old into the new schema \item old schema can be ``simulated'' via views \end{itemize} \bigskip \pause \begin{goal}{} Lossless splits can lead to \emph{more general schemas}! \begin{itemize} \item the new schema allows states which do not correspond to the state in the old schema \end{itemize} \end{goal} \begin{exampleblock}{} \recallexamplephone \emph{We may now store instructors and phone numbers without any affiliation to courses.} \end{exampleblock} % \begin{itemize} % \item If instructors without courses are possible in the real world, % the decomposition removes a fault in the old schema (insertion and % update anomalies). % % \item If they are not, % \begin{itemize} % \item a new constraint is needed that is not necessarily easier to % enforce than the FD, but % \item at least the redundancy is avoided (update anomaly). % \end{itemize} % \end{itemize} \end{frame}