How are log sequence numbers used by ARIES to reduce the amount of REDO work needed for recovery? Illustrate with an example using the information shown in Figure 22.5. You can make your own assumptions as to when a page is written to disk.

Figure 22.5

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(a) Lsn Last_Isn Tran_id Туре Page_id Other_information 1. update T2 update 3 commit 4 begin checkpoint 5 end checkpoint 6 T3 update A 7 2 update 8. 7 commit TRANSACTION TABLE DIRTY PAGE TABLE (b) Transaction_id Last_Isn Status Page_id Lsn 3 commit 1 T2 2 in progress TRANSACTION TABLE DIRTY PAGE TABLE (c) Transaction_id Last_Isn Status Page_id Lsn commit 7 T2 8. commit B T3 6. in progress A