An index in a DBMS is said to be dense if an index entry appears for every search-key value in the indexed file. Otherwise it is called a sparse index. Consider the following two statements. S1: A hash index must be a dense index S2: A

B^+

tree index can be a sparse index Which one of the following options is correct?

Single correct

Source: GATE CSE 2026 Set 2 (CS2), IIT Guwahati. Official question paper.

GATE CSE 2025 | Set 1 | Question 21

Indexing

MSQ1 mark

Consider the following

B^+

tree with 5 nodes, in which a node can store at most 3 key values. The value 23 is now inserted in the

B^+

tree. Which of the following options(s) is/are CORRECT?

Figure for GATE CSE 2025 | Set 1 | Question 21

One or more correct

Source: GATE CSE 2025 Set 1 (CS1), IIT Roorkee. Official question paper.

GATE CSE 2025 | Set 2 | Question 57

Indexing

NAT2 marks

In a B+- tree where each node can hold at most four key values, a root to leaf path consists of the following nodes: A = (49, 77, 83, -), B = (7, 19, 33, 44), C = (20*, 22*, 25*, 26*) The *-marked keys signify that these are data entries in a leaf. Assume that a pointer between keys

k_1

and

k_2

points to a subtree containing keys in

[k_1, k_2)

, and that when a leaf is created, the smallest key in it is copied up into its parent. A record with key value 23 is inserted into the B+- tree. The smallest key value in the parent of the leaf that contains 25* is __________. (Answer in integer)

Numerical answer

Your answer

Source: GATE CSE 2025 Set 2 (CS2), IIT Roorkee. Official question paper.

GATE CSE 2024 | Set 1 | Question 21

Indexing

MCQ1 mark

In a B+ tree, the requirement of at least half-full (50%) node occupancy is relaxed for which one of the following cases?

Single correct

Source: GATE CSE 2024 Set 1 (CS1), IISc Bengaluru. Official question paper.

GATE CSE 2024 | Set 2 | Question 26

Indexing

MSQ1 mark

Which of the following file organizations is/are I/O efficient for the scan operation in DBMS?

One or more correct

Source: GATE CSE 2024 Set 2 (CS2), IISc Bengaluru. Official question paper.

GATE CSE 2023 | Question 62

Indexing

NAT2 marks

Consider a database of fixed-length records, stored as an ordered file. The database has 25,000 records, with each record being 100 bytes, of which the primary key occupies 15 bytes. The data file is block-aligned in that each data record is fully contained within a block. The database is indexed by a primary index file, which is also stored as a block-aligned ordered file. The figure below depicts this indexing scheme. Suppose the block size of the file system is 1024 bytes, and a pointer to a block occupies 5 bytes. The system uses binary search on the index file to search for a record with a given key. You may assume that a binary search on an index file of

b

blocks takes

\lceil \log_2 b \rceil

block accesses in the worst case. Given a key, the number of block accesses required to identify the block in the data file that may contain a record with the key, in the worst case, is __________

Numerical answer

Your answer

Answer key coming soon

Source: GATE CSE 2023, IIT Kanpur. Official question paper.

GATE CSE 2021 | Set 2 | Question 21

Indexing

NAT1 mark

A data file consisting of 1,50,000 student-records is stored on a hard disk with block size of 4096 bytes. The data file is sorted on the primary key RollNo. The size of a record pointer for this disk is 7 bytes. Each student-record has a candidate key attribute called ANum of size 12 bytes. Suppose an index file with records consisting of two fields, ANum value and the record pointer to the corresponding student record, is built and stored on the same disk. Assume that the records of data file and index file are not split across disk blocks. The number of blocks in the index file is __________.

Numerical answer

Your answer

Answer key coming soon

Source: GATE CSE 2021 Set 2 (CS2), IIT Bombay. Official question paper.

GATE CSE 2020 | Question 54

Indexing

NAT2 marks

Consider a database implemented using B+ tree for file indexing and installed on a disk drive with block size of 4 KB. The size of search key is 12 bytes and the size of tree/disk pointer is 8 bytes. Assume that the database has one million records. Also assume that no node of the B+ tree and no records are present initially in main memory. Consider that each record fits into one disk block. The minimum number of disk accesses required to retrieve any record in the database is _________.

Numerical answer

Your answer

Answer key coming soon

Source: GATE CSE 2020, IIT Delhi. Official question paper.

GATE CSE 2019 | Question 14

Indexing

MCQ1 mark

Which one of the following statements is NOT correct about the B+ tree data structure used for creating an index of a relational database table?

Single correct

Source: GATE CSE 2019, IIT Madras. Official question paper and answer key.

GATE CSE 2017 | Set 2 | Question 49

Indexing

NAT2 marks

In a B+ tree, if the search-key value is 8 bytes long, the block size is 512 bytes and the block pointer size is 2 bytes, then the maximum order of the B+ tree is ________.

Numerical answer

Your answer

Answer key coming soon

Source: GATE CSE 2017 Set 2, IIT Roorkee. Official question paper.

GATE CSE 2016 | Set 2 | Question 21

Indexing

MCQ1 mark

B+ Trees are considered BALANCED because

Single correct

Answer key coming soon

Source: GATE CSE 2016 Set 2, IISc Bengaluru. Official question paper.

GATE CSE 2015 | Set 1 | Question 32

Indexing

MCQ1 mark

A file is organized so that the ordering of data records is the same as or close to the ordering of data entries in some index. Then that index is called

Single correct

Source: GATE CSE 2015 Set 1, IIT Kanpur. Official question paper and answer key.

GATE CSE 2015 | Set 2 | Question 32

Indexing

NAT1 mark

With reference to the B+ tree index of order 1 shown below, the minimum number of nodes (including the Root node) that must be fetched in order to satisfy the following query: "Get all records with a search key greater than or equal to 7 and less than 15" is _____.

Figure for GATE CSE 2015 | Set 2 | Question 32

Numerical answer

Your answer

Source: GATE CSE 2015 Set 2, IIT Kanpur. Official question paper and answer key.

GATE CSE 2015 | Set 3 | Question 39

Indexing

NAT2 marks

Consider a B+ tree in which the search key is 12 bytes long, block size is 1024 bytes, record pointer is 10 bytes long and block pointer is 8 bytes long. The maximum number of keys that can be accommodated in each non-leaf node of the tree is _____.

Numerical answer

Your answer

Source: GATE CSE 2015 Set 3, IIT Kanpur. Official question paper and answer key.

GATE CSE 2014 | Set 2 | Question 30

Indexing·Relational Algebra

MCQ2 marks

Consider a join (relation algebra) between relations r(R) and s(S) using the nested loop method. There are 3 buffers each of size equal to disk block size, out of which one buffer is reserved for intermediate results. Assuming size(r(R))<size(s(S)), the join will have fewer number of disk block accesses if

Single correct

Source: GATE CSE 2014 Set 2, IIT Kharagpur. Official question paper and answer key.

GATE CSE 2013 | Question 15

Indexing

MCQ1 mark

An index is clustered, if

Single correct

Answer key coming soon

Source: GATE CSE 2013, IIT Bombay. Official question paper (booklet code A).

GATE CSE 2011 | Question 39

Indexing

MCQ2 marks

Consider a relational table

r

with sufficient number of records, having attributes

A_1, A_2, \ldots, A_n

and let

1 \le p \le n

. Two queries Q1 and Q2 are given below. Q1:

\pi_{A_1, \ldots, A_p}(\sigma_{A_p = c}(r))

where

c

is a constant Q2:

\pi_{A_1, \ldots, A_p}(\sigma_{c_1 \le A_p \le c_2}(r))

where

c_1

and

c_2

are constants The database can be configured to do ordered indexing on

A_p

or hashing on

A_p

. Which of the following statements is TRUE?

Single correct

Answer key coming soon

Source: GATE CSE 2011, IIT Madras. Official question paper.

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