MC	Which statement is NOT CORRECT?	Even if the database contains replicated data, applying the basic 2PL protocol still suffices to guarantee serializability. 	correct	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	Primary site 2PL comes down to applying the centralized Two-Phase Locking protocol in a distributed environment. 	incorrect	
MC	Many NoSQL databases apply some form of...	horizontal fragmentation.	correct	vertical fragmentation.	incorrect	
MC	A schedule in 2PL is deadlock free if...	both the local and global wait-for graphs contain no cycles.	correct	the local wait-for graphs contain no cycles.	incorrect	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	
MC	A schedule in 2PL is deadlock free if...	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	the global wait-for graph contains only a limited number of cycles.	incorrect	
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 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	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	
MC	Which statement is NOT 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	Location transparency means that database users do not need to know on which node the required data resides.	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	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	
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?	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	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	Primary site 2PL comes down to applying the centralized Two-Phase Locking protocol in a distributed environment. 	incorrect	
MC	Which statement is CORRECT?	The CAP theorem can be criticized in that is not only the actual occurrence of network partitions that will result in the choice to abandon consistency. 	correct	The CAP theorem claims that we should always enforce three properties: Consistency, Availability and Partition tolerance.	incorrect	NoSQL databases often give up their consistency, even though this causes high costs in a big data setting. 	incorrect	Vertical fragmentation in a relational setting is often called 'sharding'. 	incorrect	
MC	Which statement is CORRECT?	In ADO.NET, transaction conflicts in DataSets are resolved by using timestamps as default.	incorrect	The DBMS implements a compensating operation for each possible operation. 	incorrect	A compensating operation is not the same as a rollback. 	correct	With the 2PC protocol, the number of nodes responding with 'abort' should be above a certain threshold in order for the coordinator to abort the entire transaction. 	incorrect