MC	Which statement is CORRECT?	In a shared memory architecture, multiple interconnected processors that run the DBMS software share the same central storage and secondary storage. 	incorrect	With a shared disk architecture, each processor has its own central storage but shares secondary storage with the other processors. 	incorrect	In a shared nothing architecture, each processor has its own central storage and hard disk units.	incorrect	All statements are CORRECT.	correct	
MC	Quorum based protocols essentially enforce consistency between replicas of the same data item by means of three configurable parameters N (the number of nodes to which a data item is replicated), R (the minimum number of nodes that should respond before a read operation for a data item can be considered as completed) and W (the minimum number of nodes that should receive the updated value before a write operation for a data item can be considered as completed), with R <= N and W <= N.<br><br>Which statement is NOT CORRECT?	By manipulating R and W, the database administrator can decide on the trade-off between performance and consistency, but also on the trade-off between read performance and write performance. 	incorrect	A higher N also allows for more parallelism, but at the same time increases the overhead if one needs to keep all N replicas permanently consistent.	incorrect	A higher R increases the chance that the set of replicas that is returned by these R nodes contains an up to date version of the data item.	incorrect	The higher W is, the faster the write performance, since the response time is determined by the fastest of these W nodes. 	correct	
MC	With BASE transactions, conflict resolution...	always happens at the moment of writing the data.	incorrect	may be postponed until the data is actually read.	correct	
MC	Which statement is NOT CORRECT?	Transaction transparency refers to the fact that the distributed database can be accessed and queried in a uniform fashion, regardless of the different database systems and APIs that may be involved. 	correct	Fragmentation transparency refers to the fact that users can execute global queries, without being concerned with the fact that distributed fragments will be involved, and need to be combined, to perform the query.	incorrect	Replication transparency means that different replicas of the same data item will be automatically kept consistent by the database system and updates to one replica will be propagated transparently (be it synchronously or asynchronously) to the other copies of the same data item.	incorrect	Location transparency means that database users do not need to know on which node the required data resides.	incorrect	
MC	Which statement is NOT CORRECT?	Even if the database contains replicated data, applying the basic 2PL protocol still suffices to guarantee serializability. 	correct	Primary site 2PL comes down to applying the centralized Two-Phase Locking protocol in a distributed environment. 	incorrect	With distributed 2PL, every site has its own lock manager, which is responsible for managing all locking data pertaining to the fragments stored on that site. 	incorrect	A disadvantage of Primary site 2PL is that the central lock manager may become a bottleneck.	incorrect	
MC	A schedule in 2PL is deadlock free if...	the global wait-for graph contains only a limited number of cycles.	incorrect	the local wait-for graph contains only a limited number of cycles.	incorrect	both the local and global wait-for graphs contain no cycles.	correct	the local wait-for graphs contain no cycles.	incorrect	
MC	Eventual consistency in a NoSQL environment implies that...	the database is consistent at all times.	incorrect	the database is inconsistent at all times.	incorrect	the results of a database transaction will immediately be propagated to all replicas.	incorrect	the results of a database transaction will eventually be propagated to all replicas and if no further transactions are executed then the system will eventually become consistent.	correct	
MC	With horizontal fragmentation...	each fragment consists of rows that satisfy a certain query predicate.	correct	each fragment consists of a subset of the columns of the global data set.	incorrect	
MC	Which statement is CORRECT?	In a shared memory architecture, multiple interconnected processors that run the DBMS software share the same central storage and secondary storage. 	incorrect	With a shared disk architecture, each processor has its own central storage but shares secondary storage with the other processors. 	incorrect	In a shared nothing architecture, each processor has its own central storage and hard disk units.	incorrect	All statements are CORRECT.	correct	
MC	Quorum based protocols essentially enforce consistency between replicas of the same data item by means of three configurable parameters N (the number of nodes to which a data item is replicated), R (the minimum number of nodes that should respond before a read operation for a data item can be considered as completed) and W (the minimum number of nodes that should receive the updated value before a write operation for a data item can be considered as completed), with R <= N and W <= N.<br><br>Which statement is NOT CORRECT?	The higher W is, the faster the write performance, since the response time is determined by the fastest of these W nodes. 	correct	A higher R increases the chance that the set of replicas that is returned by these R nodes contains an up to date version of the data item.	incorrect	By manipulating R and W, the database administrator can decide on the trade-off between performance and consistency, but also on the trade-off between read performance and write performance. 	incorrect	A higher N also allows for more parallelism, but at the same time increases the overhead if one needs to keep all N replicas permanently consistent.	incorrect