RDBMS Questions and Answers – B+ trees

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This set of RDBMS Multiple Choice Questions & Answers (MCQs) focuses on “B+ Tree Index Files”.

1. State true or false: B+ trees are not always balanced trees.
a) True
b) False
View Answer

Answer: b
Explanation: B+ trees are always balanced. Every path from the root to the leaf of the tree is of the same length.
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2. What are the leaf nodes in a B+ tree?
a) The topmost nodes
b) The bottommost nodes
c) The nodes in between the top and bottom nodes
d) None of the mentioned
View Answer

Answer: b
Explanation: The bottommost nodes that mark the end of a tree are known as the leaf nodes in a B+ tree.

3. Non-leaf nodes are also called as __________
a) Internal nodes
b) External nodes
c) Middle nodes
d) Primary nodes
View Answer

Answer: a
Explanation: Non leaf nodes are also known as internal nodes. A non-leaf node may hold up to n pointers and should hold at least n/2 pointers.

4. The queries used to find all records with search key values in a particular range are known as ________
a) Gap queries
b) Graph queries
c) Range queries
d) None of the mentioned
View Answer

Answer: c
Explanation: The queries used to find all records with search key values in a particular range are known as Range queries. These type of queries are executed using procedures.
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5. Statement 1: Insertion of record might require the change in position of the initial nodes.
Statement 2: Deletion of records might require the change in position of the initial nodes.
a) Both the statements are true
b) Statement 1 is true but statement 2 is false
c) Statement 2 is true but statement 1 is false
d) Both the statements are false
View Answer

Answer: a
Explanation: Both insertion and deletion of records might require the change in position of the initial nodes because the new data value might not exactly fit into the B+ tree. Thus rotation of the nodes is generally required.

6. If a relation can have more than one record containing the same search key value, the search key is said to be a __________
a) Unique search key
b) Non unique search key
c) Multiple search key
d) Identical search key
View Answer

Answer: b
Explanation: If a relation can have more than one record containing the same search key value, the search key is said to be a non-unique search key. A problem with non-unique search keys is inefficiency during delete operations.

7. State true or false: The fanout of nodes can be increased by using a technique called _________
a) Prefix compression
b) Postfix compression
c) Prefix expansion
d) Postfix expansion
View Answer

Answer: a
Explanation: The fanout of nodes can be increased by using a technique called prefix compression. In this, we do not store the entire value of the search key at the node. We only store the prefix of the search key.
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8. Insertion of a large number of entries at a time into an index is referred to as _______ of the index.
a) Bulk loading
b) Mass insertion
c) Quick insertion
d) Quick loading
View Answer

Answer: a
Explanation: Insertion of a large number of entries at a time into an index is referred to as bulk loading of the index. This reduces the time complexity as multiple entries are loaded at the same time.

9. ___________ are the indices that store the values of some attributes along with the pointers to the recor.
a) Binary indices
b) Covering indices
c) Key indices
d) Static indices
View Answer

Answer: b
Explanation: Covering indices are the indices that store the values of some attributes along with the pointers to the record. Storing extra attribute values is useful as they allow us to Answer queries without actually looking up the records.

Sanfoundry Global Education & Learning Series – RDBMS.

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer & SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage, Advanced C Programming, SAN Storage Technologies, SCSI Internals & Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him @ LinkedIn