MC	Which of the following statements on concurrency control is not correct?	A pessimistic protocol will delay the execution of the operations more than an optimistic protocol.	incorrect	An optimistic protocol assumes that conflicts between simultaneous transactions are exceptional.	incorrect	Common techniques in scheduling are timestamping and locking.	incorrect	A serial scheduler is an extreme version of an optimistic scheduler.	correct	
MC	According to the MGL-Protocol, 	locks are acquired top-down, but released bottom-up in the hierarchy.	correct	locks are acquired bottom-up, but released top-down in the hierarchy.	incorrect	
MC	Which statement is NOT CORRECT?	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.	incorrect	A transaction is a set of database operations (e.g. a consecution of SQL statements in a relational database), induced by a single user or application, that should be considered as one undividable unit of work.	incorrect	Recovery is the activity of ensuring that, whichever problem occurred, the database is returned to a consistent state afterwards, without any data loss. 	incorrect	Transactions typically exist in isolation, and cannot be executed concurrently with other transactions on the same data.	correct	
MC	If the precedence graph contains a cycle, the schedule is...	not serializable	correct	serializable	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	According to the MGL-Protocol, 	locks are acquired bottom-up, but released top-down in the hierarchy.	incorrect	locks are acquired top-down, but released bottom-up in the hierarchy.	correct	
MC	Which statement is CORRECT?	If the precedence graph contains a cycle, the schedule is serializable.	incorrect	The logfile contains all updates after they have been written to disk. 	incorrect	The logfile is often duplicated, e.g. in a RAID level 1 configuration.	correct	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	
MC	Which of the following statements on locking is not correct?	Deadlock prevention can be achieved by implementing static 2PL. 	incorrect	A repeatable read does not solve the phantom read problem. 	incorrect	A six-lock in the MGL protocol conflicts with all other locks. 	correct	A 'serializable' isolation level is almost equal to 2PL. 	incorrect	
MC	Which of the following statements on locking is correct?	Deadlock detection and resolution is often more preferable than deadlock prevention. 	correct	Cascading rollbacks can be solved by implementing static 2PL. 	incorrect	Static 2PL enforces that all locks can only be released once the transaction is committed. 	incorrect	With a 'read committed' isolation level, the problems of lost update, uncommitted dependency and inconsistent analysis are solved. 	incorrect	
MC	Which of the following statements on concurrency control is correct?	A lost update problem, uncommitted dependency problem or inconsistent analysis problem will always lead to an inconsistent database state.	incorrect	N transactions lead to N<sup>2</sup> different serial schedules.	incorrect	A schedule is serializable if its precedence graph contains a cycle.	incorrect	None of the above.	correct