c) Given the scenarios described by the transaction log in Figure Q4c, explain the database recovery procedure for transactions T1 to T4. Record Pointer Transaction ID Reverse Pointer Time Type of Operation Table Row ID Before Image After Image T1 Start Forward Pointer T1 Insert SupplierOrder 52 52, 7, ... . T2 T2 T2 12:01:32 12:01:36 12:01:55 12:02:01 12:02:24 12:04:26 12:05:00 Start Insert Update Start Update Orderltem Item A123,3 7 A123, 3, 7, ... 7, 15, ... 7, 31, ... T3 T3 7 Item 7, 15, ... 7,3,... 7 Checkpoint 8 2 T1 T3 0 12 7 Item 10 10, 22, ... 10, 3, ... 9 10 11 12 13 T4 T4 11 13 12:05:41 12:06:23 12:35:33 12:35:36 12:36:36 12:37:33 Rollback Update Start insert Commit Insert 10 SupplierOrder 52 52, 7, ... 9 0 T3 T4 11 0 53, 10, ... SupplierOrder 53 Crash! Figure Q4c (10 marks) c) Given the scenarios described by the transaction log in Figure Q4c, explain the database recovery procedure for transactions T1 to T4. Record Pointer Transaction ID Reverse Pointer Time Type of Operation Table Row ID Before Image After Image T1 Start Forward Pointer T1 Insert SupplierOrder 52 52, 7, ... . T2 T2 T2 12:01:32 12:01:36 12:01:55 12:02:01 12:02:24 12:04:26 12:05:00 Start Insert Update Start Update Orderltem Item A123,3 7 A123, 3, 7, ... 7, 15, ... 7, 31, ... T3 T3 7 Item 7, 15, ... 7,3,... 7 Checkpoint 8 2 T1 T3 0 12 7 Item 10 10, 22, ... 10, 3, ... 9 10 11 12 13 T4 T4 11 13 12:05:41 12:06:23 12:35:33 12:35:36 12:36:36 12:37:33 Rollback Update Start insert Commit Insert 10 SupplierOrder 52 52, 7, ... 9 0 T3 T4 11 0 53, 10, ... SupplierOrder 53 Crash! Figure Q4c (10 marks)