\begin{frame} \frametitle{Intention Locks} \begin{goal}{} Databases use an additional type of locks: \emph{intention locks}. \begin{itemize} \item Lock mode \emph{intention share (IS)} \item Lock mode \emph{intention exclusive (IX)} \end{itemize} Before introducing S (or X) lock, first IS (or IX) locks on all coarser levels of granularity. \end{goal} \pause\medskip \begin{block}{Extended lock conflict matrix} \begin{center} \begin{tabular}{c|c c c c } & S & X & IS & IX\\ \hline S & & \alert{x} & & \alert{x} \\ X & \alert{x} & \alert{x} & \alert{x} & \alert{x} \\ IS & & \alert{x} & & \\ IX & \alert{x} & \alert{x} & & \end{tabular} \end{center} \end{block} \end{frame}