MC	Which statement is CORRECT?	The logfile contains all updates after they have been written to disk. 	incorrect	The lost update problem not always results in an inconsistent database state, whereas an uncommitted dependency or inconsistent analysis always yields an inconsistent database state.	incorrect	If the precedence graph contains a cycle, the schedule is serializable.	incorrect	It should not be possible to terminate a transaction in such a way that the database remains in an inconsistent state, because some operations of a single transaction were executed successfully and others were not.	correct	
MC	Which statement is NOT CORRECT?	An optimistic protocol assumes that conflicts between simultaneous transactions are exceptional.	incorrect	The logfile is often duplicated, e.g. in a RAID level 1 configuration.	incorrect	The lost update problem not always results in an inconsistent database state, whereas an uncommitted dependency or inconsistent analysis always yields an inconsistent database state.	correct	The use of short-term locks violates rule 3 of the 2PL protocol, so serializability can no longer be guaranteed.	incorrect	
MC	Which statement is NOT CORRECT?	The logfile contains redundant data.	incorrect	The logfile is often duplicated, e.g. in a RAID level 1 configuration.	incorrect	The logfile can be implemented as a sequential file.	incorrect	The logfile contains all updates after they have been written to disk. 	correct	
MC	The following figure presents five transactions (T1 until T5) that are executed more or less simultaneously. Suppose a checkpoint was registered on the logfile at time tc, marking the last time when pending updates in the database buffer were persisted into the physical database files. Later, at time tf, a system fault occurred, resulting in loss of the database buffer.<br><img class="img-fluid" src="http://www.pdbmbook.com/static/quiz/fig14_5.png"><br>What recovery operations are required?	T1: nothing; T2: REDO; T3: UNDO; T4: REDO; T5: nothing	correct	T1: REDO; T2: UNDO; T3: REDO; T4: nothing; T5: nothing	incorrect	T1: nothing; T2: UNDO; T3: REDO; T4: REDO; T5: nothing	incorrect	T1: nothing; T2: REDO; T3: REDO; T4: REDO; T5: nothing	incorrect	
MC	Which statement is CORRECT?	Multiple transactions may hold a shared lock on the same object.	correct	Multiple transactions may hold an exclusive lock on the same object.	incorrect	
MC	Which of the following DBMS components is involved in Transaction Management?	Scheduler	incorrect	Stored data manager	incorrect	Buffer manager	incorrect	Recovery manager	incorrect	All of these components	correct	
MC	Which of the following DBMS components is involved in Transaction Management?	Scheduler	incorrect	Stored data manager	incorrect	Buffer manager	incorrect	Recovery manager	incorrect	All of these components	correct	
MC	When a transaction is aborted, it is important that:	All changes made by the individual operations belonging to that transaction should be made permanent.	incorrect	A rollback of the transaction is executed: all changes made by the transaction's respective operations should be undone.	correct	
MC	Which statement is CORRECT?	Multiple transactions may hold an exclusive lock on the same object.	incorrect	Multiple transactions may hold a shared lock on the same object.	correct	
MC	Which statement is NOT CORRECT?	The logfile can be implemented as a sequential file.	incorrect	The logfile is often duplicated, e.g. in a RAID level 1 configuration.	incorrect	The logfile contains redundant data.	incorrect	The logfile contains all updates after they have been written to disk. 	correct