Indexing (B-trees, hash indexing) MCQs in DBMS

1. What is the primary purpose of using B-trees in indexing?

(A) To store data sequentially

(B) To maintain sorted data and allow searches, insertions, deletions in logarithmic time

(C) To provide direct access to records

(D) To minimize disk space usage

2. In a B-tree of order m, what is the maximum number of children a node can have?

(A) m-1

(B) m

(C) m+1

(D) 2m

3. Which property is unique to B+ trees compared to B-trees?

(A) All values are stored at leaf nodes and internal nodes store only keys

(B) Values can be stored at both internal and leaf nodes

(C) Nodes can have a variable number of children

(D) Leaf nodes are linked together to form a linked list

4. What is a major advantage of using a B+ tree over a B-tree for indexing?

(A) Faster insertions and deletions

(B) Sequential access to records is easier

(C) Better handling of duplicate keys

(D) Requires less memory

5. In a hash index, what is the purpose of a hash function?

(A) To sort the keys

(B) To encrypt the data

(C) To compute the address of the data record

(D) To compress the data

6. Which of the following is a disadvantage of hash indexing?

(A) Inefficient for range queries

(B) Slow search performance

(C) High memory usage

(D) Complexity in implementation

7. In B-trees, what happens when a node becomes full and a new key is inserted?

(A) The node is split into two nodes

(B) The new key is discarded

(C) The tree is rebalanced

(D) The node is expanded to accommodate the new key

8. What is the height of a B-tree with ‘n’ keys and minimum degree ‘t’?

(A) logₜ(n)

(B) logₜ(n+1)

(C) logₜ((n+1)/2)

(D) logₜ((n−1)/2)

9. Which type of index is more efficient for exact-match queries?

(A) B-tree index

(B) B+ tree index

(C) Hash index

(D) Dense index

10. How does a B+ tree handle insertions when the leaf node is full?

(A) By creating a new tree

(B) By splitting the leaf node and adjusting the parent node

(C) By shifting the existing keys

(D) By merging with an adjacent node

11. In a hash table, what is a ‘collision’?

(A) When two keys generate the same hash value

(B) When a key is not found

(C) When the table is resized

(D) When a key is deleted

12. Which of the following statements is true about B+ trees?

(A) They allow binary search

(B) They do not maintain sorted order

(C) They have all data at the leaf level

(D) They do not support sequential access