\begin{frame} \frametitle{Conflicts} \begin{goal}{} Two actions in a schedule \emph{conflict} if they: \begin{itemize} \item are from \emph{different transactions}, \item involve the \emph{same data item}, and \item \emph{one of the actions is a write}. \smallskip \end{itemize} \end{goal} \begin{exampleblock}{} \begin{tcenter} \begin{tikzpicture} \schedule{}{2}{1rY|1wY!1+3|2rY!1+3|2wZ|1wX} \end{tikzpicture} \end{tcenter} \end{exampleblock} \pause\pause\medskip \begin{goal}{} There are several types of \emph{conflicts}: \begin{itemize} \item \emph{write read} (WR) \item \emph{read write} (RW) \item \emph{write write} (WW) \smallskip \end{itemize} \end{goal} \pause\medskip \begin{alertblock}{} Such conflicts may cause a schedule to be not serializable. \end{alertblock} \end{frame}