Engineering Questions with Answers - Multiple Choice Questions
B+ Tree MCQ’s
1 - Question
In a B+ tree, both the internal nodes and the leaves have keys.
a) True
b) False
View Answer
Answer: b
Explanation: In a B+ -tree, only the leaves have keys, and these keys are replicated in non-leaf nodes for defining the path for locating individual records.
2 - Question
Which of the following is true?
a) B + tree allows only the rapid random access
b) B + tree allows only the rapid sequential access
c) B + tree allows rapid random access as well as rapid sequential access
d) B + tree allows rapid random access and slower sequential access
View Answer
Answer: c
Explanation: The B+ -tree being a variation of B-tree allows rapid random access. In a B+ -tree the leaves are linked together, so it also provides rapid sequential access.
3 - Question
A B+ tree can contain a maximum of 7 pointers in a node. What is the minimum number of keys in leaves?
a) 6
b) 3
c) 4
d) 7
View Answer
Answer: b
Explanation: Maximum number of pointers in a node is 7, i.e. the order of the B+ -tree is 7. In a B+ tree of order n each leaf node contains at most n – 1 key and at least ⌈(n − 1)/2⌉ keys. Therefore, a minimum number of keys each leaf can have = ⌈(7 – 1)/2⌉ = 3.
4 - Question
Which of the following is false?
a) A B+ -tree grows downwards
b) A B+ -tree is balanced
c) In a B+ -tree, the sibling pointers allow sequential searching
d) B+ -tree is shallower than B-tree
View Answer
Answer: a
Explanation: A B+ -tree always grows upwards. And In a B+tree – i)The path from the root to every leaf node is of the same length, so the tree is balanced. ii) Leaves are linked, so allow sequential searching. iii) An index is built with a single key per block of data rather than with one key per data record, so it is shallower than B-tree.
5 - Question
A B+ -tree of order 3 is generated by inserting 89, 9 and 8. The generated B+ -tree is __________
a)
b)
c)
d)
View Answer
Answer: b
Explanation:
6 - Question
Statement 1: When a node is split during insertion, the middle key is promoted to the parent as well as retained in right half-node.
Statement 2: When a key is deleted from the leaf, it is also deleted from the non-leaf nodes of the tree.
a) Statement 1 is true but statement 2 is false
b) Statement 2 is true but statement 1 is false
c) Both the statements are true
d) Both the statements are false
View Answer
Answer: a
Explanation: During the split, the middle key is retained in the right half node and also promoted to parent node. When a key is deleted from the leaf, it is retained in non-leaves, because it can be still a valid separator between keys in nodes below.
7 - Question
Efficiency of finding the next record in B+ tree is ____
a) O(n)
b) O(log n)
c) O(nlog n)
d) O(1)
View Answer
Answer: d
Explanation: In a B+ -tree finding the next recored (successor) involves accessing an additional leaf at most. So, the efficiency of finding the next record is O(1).
8 - Question
What is the maximum number of keys that a B+ -tree of order 3 and of height 3 have?
a) 3
b) 80
c) 27
d) 26
View Answer
Answer: d
Explanation: A B+ tree of order n and height h can have at most nh – 1 keys. Therefore maximum number of keys = 33 -1 = 27 -1 = 26.
9 - Question
Which of the following is false?
a) Compared to B-tree, B+ -tree has larger fanout
b) Deletion in B-tree is more complicated than in B+ -tree
c) B+ -tree has greater depth than corresponding B-tree
d) Both B-tree and B+ -tree have same search and insertion efficiencies
View Answer
Answer: c
Explanation: A B+ -tree has larger fanout and therefore have a depth smaller than that of corresponding B-tree.
10 - Question
Which one of the following data structures are preferred in database-system implementation?
a) AVL tree
b) B-tree
c) B+ -tree
d) Splay tree
View Answer
Answer: c
Explanation: The database-system implementations use B+ -tree data structure because they can be used for multilevel indexing.