Indexes(Engineering > Computer Science And Engineering > Dbms Questions And Answers ) Questions and Answers

Question 1. Does index take space in the disk ?
  1.    It stores memory as and when required
  2.    Yes, Indexes are stored on disk
  3.    Indexes are never stored on disk
  4.    Indexes take no space
Explanation:-
Answer: Option B. -> Yes, Indexes are stored on disk


Yes, Indexes are stored on diskIndexes take memory slots which are located on the disk.


Question 2. In _______________ index instead of storing all the columns for a record together, each column is stored separately with all other rows in an index.
  1.    Clustered
  2.    Column store
  3.    Non clustered
  4.    Row store
Explanation:-
Answer: Option B. -> Column store


Column storeA database index is a data structure that improves the speed of data retrieval operations on a database table at the cost of additional writes.


Question 3. If an index is _________________ the metadata and statistics continue to exists
  1.    Disabling
  2.    Dropping
  3.    Altering
  4.    Both a and b
Explanation:-
Answer: Option A. -> Disabling


DisablingA database index is a data structure that improves the speed of data retrieval operations on a database table at the cost of additional writes.


Question 4. What are composite indexes ?
  1.    Are those which are composed by database for its internal use
  2.    A composite index is a combination of index on 2 or more columns
  3.    Composite index can never be created
  4.    None of the mentioned
Explanation:-
Answer: Option B. -> A composite index is a combination of index on 2 or more columns


A composite index is a combination of index on 2 or more columnsA composite index is an index on two or more columns of a table.


Question 5. A _________________ index is the one which satisfies all the columns requested in the query without performing further lookup into the clustered index.
  1.    Clustered
  2.    Non Clustered
  3.    Covering
  4.    B-Tree
Explanation:-
Answer: Option C. -> Covering


CoveringA covered query is a query where all the columns in the query's result set are pulled from non-clustered indexes.


Question 6. What is the purpose of index in sql server
  1.    To enhance the query performance
  2.    To provide an index to a record
  3.    To perform fast searches
  4.    All of the mentioned
Explanation:-
Answer: Option D. -> All of the mentioned


All of the mentionedA database index is a data structure that improves the speed of data retrieval operations on a database table at the cost of additional writes.


Question 7. How many types of indexes are there in sql server?
  1.    1
  2.    2
  3.    3
  4.    4
Explanation:-
Answer: Option B. -> 2


2They are clustered index and non clustered index.


Question 8. How non clustered index point to the data?
  1.    It never points to anything
  2.    It points to a data row
  3.    It is used for pointing data rows containing key values
  4.    None of the mentioned
Explanation:-
Answer: Option C. -> It is used for pointing data rows containing key values


It is used for pointing data rows containing key valuesNonclustered 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.


Question 9. Which one is true about clustered index?
  1.    Clustered index is not associated with table
  2.    Clustered index is built by default on unique key columns
  3.    Clustered index is not built on unique key columns
  4.    None of the mentioned
Explanation:-
Answer: Option B. -> Clustered index is built by default on unique key columns


Clustered index is built by default on unique key columnsNonclustered 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.


Question 10. What is true about indexes?
  1.    Indexes enhance the performance even if the table is updated frequently
  2.    It makes harder for sql server engines to work to work on index which have large keys
  3.    It doesn't make harder for sql server engines to work to work on index which have large keys
  4.    None of the mentioned
Explanation:-
Answer: Option B. -> It makes harder for sql server engines to work to work on index which have large keys


It makes harder for sql server engines to work to work on index which have large keysIndexes tend to improve the performance.


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