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Data Mgmt Lab_Part_62

# Data Mgmt Lab_Part_62 - 184 Chapter 18 LSN LSN LSN LSN LSN...

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184 Chapter 18 LSN 20 Add (T1,20) to TT and (P1,20) to DPT LSN 30 Add (T2,30) to TT and (P2,30) to DPT LSN 40 Add (T3,40) to TT and (P3,40) to DPT LSN 50 Change status of T2 to C LSN 60 Change (T3,40) to (T3,60) LSN 70 Remove T2 from TT LSN 80 Change (T1,20) to (T1,70) and add (P5,70) to DPT LSN 90 No action At the end of analysis, the transaction table contains the following entries: (T1,80), and (T3,60). The Dirty Page Table has the following entries: (P1,20), (P2,30), (P3,40), and (P5,80). 3. Redo starts from LSN20 (minimum recLSN in DPT). LSN 20 Check whether P1 has pageLSN more than 10 or not. Since it is a committed transaction, we probably need not redo this update. LSN 30 Redo the change in P2 LSN 40 Redo the change in P3 LSN 50 No action LSN 60 Redo the changes on P2 LSN 70 No action LSN 80 Redo the changes on P5 LSN 90 No action 4. ToUndo consists of (80, 60). LSN 80 Undo the changes in P5. Append a CLR: Undo T1 LSN 80, set undonextLSN = 20. Add 20 to ToUndo. ToUndo consists of (60, 20). LSN 60 Undo the changes on P2. Append a CLR: Undo T3 LSN 60, set undonextLSN = 40. Add 40 to ToUndo. ToUndo consists of (40, 20). LSN 40 Undo the changes on P3. Append a CLR: Undo T3 LSN 40, T3 end ToUndo consists of (20).

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