Suppose that 2PC is used as a commit protocol.

4. [20 pts] Suppose that 2PC is used as a commit protocol. Consider the following parts of recovery sub-scenarios for a distributed transaction T with coordinator C and two participating sites P1 and P2: 11 P2 checks its log and then aborts. 12 P1 sends query status request to P2 and then commits. 1.3 P1 sends query status request to P2 and then waits for messages from C 14 P1 doesn't checks its log, but do T. Consider the following cases (a) P1 fails after receiving a commit message for T. (b) Pl fails after receiving an abort message for T. (c) The coordinator site for T fails before sending a commit message. (d) P1 fails after sending a ready message for T, and then the coordinator site for T fails after sending a commit message Pl fails after sending a ready message for T, and at the same time, the coordinator site for T also fails. (e) For each of the recovery sub-scenarios specify a group of above cases that are possible for that sub-scenario. Your answer should be represented as the following table with an explanation Sub-scenario Possible cases (e.g., (a).(b),...) 1.2 1.3 4. [20 pts] Suppose that 2PC is used as a commit protocol. Consider the following parts of recovery sub-scenarios for a distributed transaction T with coordinator C and two participating sites P1 and P2: 11 P2 checks its log and then aborts. 12 P1 sends query status request to P2 and then commits. 1.3 P1 sends query status request to P2 and then waits for messages from C 14 P1 doesn't checks its log, but do T. Consider the following cases (a) P1 fails after receiving a commit message for T. (b) Pl fails after receiving an abort message for T. (c) The coordinator site for T fails before sending a commit message. (d) P1 fails after sending a ready message for T, and then the coordinator site for T fails after sending a commit message Pl fails after sending a ready message for T, and at the same time, the coordinator site for T also fails. (e) For each of the recovery sub-scenarios specify a group of above cases that are possible for that sub-scenario. Your answer should be represented as the following table with an explanation Sub-scenario Possible cases (e.g., (a).(b),...) 1.2 1.3