\begin{frame} \frametitle{Cascading Rollbacks} \begin{quiz}{\textwidth}{What is the problem here?} \begin{center} {\def\scheduleWidth{.8cm}\small \begin{tikzpicture} \schedule{}{2}{1xA|1sB|1wA!1+2|1uA|2sA|2rA!1+2|2xA|2wA|2uA|1rB|1uB} \end{tikzpicture} } \end{center} Assume that: \begin{itemize} \item $T_1$ is aborted (due to a conflict with another transaction) \item $T_2$ tries to commit \end{itemize} \medskip What is the problem here? \pause \begin{itemize} \item $T_2$ has read a value written by $T_1$. \pause \item Thus if $T_1$ is aborted, then \alert{$T_2$ needs to be aborted too}. \\ \remark{The commit will result in an abort.} \end{itemize} \end{quiz} \end{frame}