Lock Table I23 Black rectangles indicate granted locks, white ones indicate waiting requests T23 T8 T2 Lock table also records the type of lock granted or requested I912 New request is added to the end of the queue of requests for the data item,and T23 granted if it is compatible with all earlier locks Unlock requests result in the request being deleted,and later requests are checked to see if they can now be T1T23 granted 144 If transaction aborts,all waiting or ■ Granted granted requests of the transaction are deleted T8 Waiting lock manager may keep a list of locks held by each transaction,to implement this efficiently Database System Concepts-5th Edition,Oct 5,2006 16.15 @Silberschatz,Korth and SudarshanDatabase System Concepts - 5 16.15 ©Silberschatz, Korth and Sudarshan th Edition, Oct 5, 2006 Lock Table Black rectangles indicate granted locks, white ones indicate waiting requests Lock table also records the type of lock granted or requested New request is added to the end of the queue of requests for the data item, and granted if it is compatible with all earlier locks Unlock requests result in the request being deleted, and later requests are checked to see if they can now be granted If transaction aborts, all waiting or granted requests of the transaction are deleted lock manager may keep a list of locks held by each transaction, to implement this efficiently Granted Waiting