MC	Which statement is CORRECT?	NoSQL databases often give up their consistency, even though this causes high costs in a big data setting. 	incorrect	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	Vertical fragmentation in a relational setting is often called 'sharding'. 	incorrect	
MC	Which statement is CORRECT?	Even if the database contains replicated data, applying the basic 2PL protocol still suffices to guarantee serializability. 	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. 	incorrect	Primary site 2PL comes down to applying the centralized Two-Phase Locking protocol in a distributed environment. 	correct	A schedule in 2PL is deadlock free if the local 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?	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	Many NoSQL databases apply some form of...	horizontal fragmentation.	correct	vertical fragmentation.	incorrect	
MC	With BASE transactions, conflict resolution...	may be postponed until the data is actually read.	correct	always happens at the moment of writing the data.	incorrect	
MC	Assume we want to achieve fast writes, but reads are not as important. Which of the following settings for quorum-based consistency are not appropriate in this context?	A low W, like W = 1.	incorrect	R = 1 and W = N.	correct	R + W <= N.	incorrect	All of the above are good settings in this context.	incorrect	
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 of the following statements on distributed databases is not correct?	A shared-nothing architecture shares data solely by communicating over the network.	incorrect	A shared-disk architecture is typically more fault tolerant than a shared-memory architecture.	incorrect	In a shared-memory architecture, the network may become a bottleneck.	correct	Parallel databases offer data distribution for one main purpose: performance.	incorrect	
MC	Which statement is CORRECT?	Vertical fragmentation in a relational setting is often called 'sharding'. 	incorrect	The CAP theorem claims that we should always enforce three properties: Consistency, Availability and Partition tolerance.	incorrect	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	NoSQL databases often give up their consistency, even though this causes high costs in a big data setting. 	incorrect	
MC	Many NoSQL databases apply some form of...	horizontal fragmentation.	correct	vertical fragmentation.	incorrect