MC Which statement is CORRECT? Replicas in a distributed NoSQL environment relate to making periodic backups of the database to a second system. incorrect Some relational constructs, such as the many-to-many relationship, are harder to express using graph databases. incorrect The fact that most NoSQL databases adopt an eventual consistency approach is due to the CAP theorem, which states that strong consistency cannot be obtained when availability and partitioning has to be ensured. correct Stabilization relates to the waiting time between the start-up of a NoSQL system and when the system becomes usable to receive user queries. incorrect
MC Which of the following is not a property of a good hash function for use in key-value based storage structures? A hash function should always return the same output for the same input. incorrect Two hashes from two inputs that differ little should also differ as little as possible. correct A hash function should return an output of fixed size. incorrect A good hash function should map its inputs as evenly as possible over the output range. incorrect
MC Which statement is NOT CORRECT? The meaning of NoSQL shifted from 'not SQL' to 'not only SQL' or 'not relational'. incorrect The fact that most NoSQL databases adopt an eventual consistency approach is due to the CAP theorem, which states that strong consistency cannot be obtained when availability and partitioning has to be ensured. incorrect Column oriented databases are more efficient when a lot of JOINs need to be performed in queries. correct Vertical scaling is limited by hardware performance. incorrect
MC Which of the following statements describes NoSQL databases best? NoSQL databases are not capable to deal with large datasets. incorrect NoSQL databases do not support joins. incorrect NoSQL databases are non-relational. correct A NoSQL database offers no support for SQL. incorrect
MC Which of the following is not a property of a good hash function for use in key-value based storage structures? A good hash function should map its inputs as evenly as possible over the output range. incorrect A hash function should always return the same output for the same input. incorrect A hash function should return an output of fixed size. incorrect Two hashes from two inputs that differ little should also differ as little as possible. correct
MC Using Cypher, how do you get a list of all movies Wilfried Lemahieu has liked, when he has given at least four stars? MATCH (b:User)--(m:Movie)
WHERE b.name = "Wilfried Lemahieu"
AND l.stars >= 4
RETURN m incorrect SELECT (b:User)--m:Movie)
WHERE b.name = "Wilfried Lemahieu"
AND m.starts >= 4 incorrect MATCH (b:User)-[I:LIKES]-(m:Movie)
WHERE b.name = "Wilfried Lemahieu"
AND l.stars >= 4
RETURN m correct MATCH (b:User)-[I:LIKES]-(m:Movie)
WHERE b.name = "Wilfried Lemahieu"
AND m.stars >=4
RETURN m incorrect
MC What does the following Cypher query express?
OPTIONAL MATCH (user;User)-[:FRIENDS_WITH]-(friend;User)
WHERE user.name = "Bart Baesens"
RETURN user, count(friend) AS NumberOfFriends Get the node for Bart Baesens and all his friends. incorrect Get the node for Bart Baesens and a count of all his friends, even if no FRIENDS_WITH relation exists. incorrect Get the node for Bart Baesens and a count of all his friends, but only if at least one FRIENDS_WITH relation exists. correct This query will fail if Bart Baesens is FRIENDS_WITH himself. incorrect
MC Which statement is CORRECT? The fact that most NoSQL databases adopt an eventual consistency approach is due to the CAP theorem, which states that strong consistency cannot be obtained when availability and partitioning has to be ensured. correct Replicas in a distributed NoSQL environment relate to making periodic backups of the database to a second system. incorrect Some relational constructs, such as the many-to-many relationship, are harder to express using graph databases. incorrect Stabilization relates to the waiting time between the start-up of a NoSQL system and when the system becomes usable to receive user queries. incorrect
MC Using Cypher, how do you get a list of all movies Wilfried Lemahieu has liked, when he has given at least four stars? MATCH (b:User)--(m:Movie)
WHERE b.name = "Wilfried Lemahieu"
AND l.stars >= 4
RETURN m incorrect MATCH (b:User)-[I:LIKES]-(m:Movie)
WHERE b.name = "Wilfried Lemahieu"
AND l.stars >= 4
RETURN m correct SELECT (b:User)--m:Movie)
WHERE b.name = "Wilfried Lemahieu"
AND m.starts >= 4 incorrect MATCH (b:User)-[I:LIKES]-(m:Movie)
WHERE b.name = "Wilfried Lemahieu"
AND m.stars >=4
RETURN m incorrect
MC What does the following Cypher query express?
OPTIONAL MATCH (user;User)-[:FRIENDS_WITH]-(friend;User)
WHERE user.name = "Bart Baesens"
RETURN user, count(friend) AS NumberOfFriends Get the node for Bart Baesens and all his friends. incorrect This query will fail if Bart Baesens is FRIENDS_WITH himself. incorrect Get the node for Bart Baesens and a count of all his friends, but only if at least one FRIENDS_WITH relation exists. correct Get the node for Bart Baesens and a count of all his friends, even if no FRIENDS_WITH relation exists. incorrect