Shall we track each object's state precisely by assigning a separate LSN to each object ?
No, not a good idea !
DB2 tracks each minipage's state separately by associating an LSN to each minipage, besides having an LSN for the leaf page as a whole. During the undo minipage LSN is compared to the log record's LSN. This tech. incurs too much overhead.
A single state variable (LSN) for each page is desired.
. ARIES repeats history during restart recovery before performing the rollback of a loser transaction.