Engineering Questions with Answers - Multiple Choice Questions
Database MCQ – Index Definition in SQL
1 - Question
What is the purpose of the index in sql server?
a) To enhance the query performance
b) To provide an index to a record
c) To perform fast searches
d) All of the mentioned
View Answer
Answer: d
Explanation: A database index is a data structure that improves the speed of data retrieval operations on a database table at the cost of additional writes.
2 - Question
How many types of indexes are there in sql server?
a) 1
b) 2
c) 3
d) 4
View Answer
Answer: b
Explanation: They are clustered index and non clustered index.
3 - Question
How non clustered index point to the data?
a) It never points to anything
b) It points to a data row
c) It is used for pointing data rows containing key values
d) None of the mentioned
View Answer
Answer: c
Explanation: Nonclustered indexes have a structure separate from the data rows. A nonclustered index contains the nonclustered index key values and each key value entry has a pointer to the data row that contains the key value.
4 - Question
Which one is true about clustered index?
a) Clustered index is not associated with table
b) Clustered index is built by default on unique key columns
c) Clustered index is not built on unique key columns
d) None of the mentioned
View Answer
Answer: b
Explanation: Nonclustered indexes have a structure separate from the data rows. A nonclustered index contains the nonclustered index key values and each key value entry has a pointer to the data row that contains the key value.
5 - Question
What is true about indexes?
a) Indexes enhance the performance even if the table is updated frequently
b) It makes harder for sql server engines to work to work on index which have large keys
c) It doesn’t make harder for sql server engines to work to work on index which have large keys
d) None of the mentioned
View Answer
Answer: b
Explanation: Indexes tend to improve the performance.
6 - Question
Does index take space in the disk?
a) It stores memory as and when required
b) Yes, Indexes are stored on disk
c) Indexes are never stored on disk
d) Indexes take no space
View Answer
Answer: b
Explanation: Indexes take memory slots which are located on the disk.
7 - Question
What are composite indexes?
a) Are those which are composed by database for its internal use
b) A composite index is a combination of index on 2 or more columns
c) Composite index can never be created
d) None of the mentioned
View Answer
Answer: b
Explanation: A composite index is an index on two or more columns of a table.
8 - Question
If an index is _________________ the metadata and statistics continue to exists
a) Disabling
b) Dropping
c) Altering
d) Both Disabling and Dropping
View Answer
Answer: a
Explanation: A database index is a data structure that improves the speed of data retrieval operations on a database table at the cost of additional writes.
9 - Question
In _______________ index instead of storing all the columns for a record together, each column is stored separately with all other rows in an index.
a) Clustered
b) Column store
c) Non clustered
d) Row store
View Answer
Answer: b
Explanation: A database index is a data structure that improves the speed of data retrieval operations on a database table at the cost of additional writes.
10 - Question
A _________________ index is the one which satisfies all the columns requested in the query without performing further lookup into the clustered index.
a) Clustered
b) Non Clustered
c) Covering
d) B-Tree
View Answer
Answer: c
Explanation: A covered query is a query where all the columns in the query’s result set are pulled from non-clustered indexes.