MC	Many NoSQL databases apply some form of...	horizontal fragmentation.	correct	vertical fragmentation.	incorrect	
MC	Eventual consistency in a NoSQL environment implies that...	the database is inconsistent at all times.	incorrect	the database is consistent 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	Many NoSQL databases apply some form of...	vertical fragmentation.	incorrect	horizontal fragmentation.	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?	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	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	The higher W is, the faster the write performance, since the response time is determined by the fastest of these W nodes. 	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	
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	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	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	Location transparency means that database users do not need to know on which node the required data resides.	incorrect	
MC	Optimistic concurrency may considerably increase transaction throughput and overall data availability in a...	loosely coupled setting.	correct	tightly coupled setting.	incorrect	
MC	Which statement is NOT CORRECT?	Primary site 2PL comes down to applying the centralized Two-Phase Locking protocol in a distributed environment. 	incorrect	Even if the database contains replicated data, applying the basic 2PL protocol still suffices to guarantee serializability. 	correct	A disadvantage of Primary site 2PL is that the central lock manager may become a bottleneck.	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	
MC	Optimistic concurrency may considerably increase transaction throughput and overall data availability in a...	tightly coupled setting.	incorrect	loosely coupled setting.	correct	
MC	Many NoSQL databases apply some form of...	vertical fragmentation.	incorrect	horizontal fragmentation.	correct	
MC	Which statement is NOT CORRECT?	Many NoSQL databases apply some form of horizontal fragmentation.	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	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	Eventual consistency in a NoSQL environment implies that the results of a database transaction will immediately be propagated to all replicas.	correct