44 + Interview Questions in Indexing And Hashing in Database Management Page 1 InterviewSolution

1.	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 storeThe question was posed to me during a job interview.My question is taken from Index Definition in SQL topic in portion Indexing and Hashing of Database Management
Answer» CORRECT OPTION is (B) Column store To explain: 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.

Discussion

2.	A hash function must meet ________ criteria.(a) Two(b) Three(c) Four(d) None of the mentionedI got this question during an online interview.My question comes from Ordered Indexing and Hashing topic in section Indexing and Hashing of Database Management
Answer» The CORRECT answer is (b) Three To EXPLAIN: Only if the CRITERIA is fulfilled the VALUES are hashed.

Discussion

3.	Incase the indices values are larger, index is created for these values of the index. This is called(a) Pointed index(b) Sequential index(c) Multilevel index(d) Multiple indexI have been asked this question during an interview.I want to ask this question from Ordered Indices in chapter Indexing and Hashing of Database Management
Answer» Right ANSWER is (c) MULTILEVEL index To explain: INDICES with two or more levels are called multilevel indices.

Discussion

4.	Which of the following scenarios leads to linear running time for a random search hit in a linear-probing hash table?(a) All keys hash to same index(b) All keys hash to different indices(c) All keys hash to an even-numbered index(d) All keys hash to different even-numbered indicesThe question was posed to me in an internship interview.I'd like to ask this question from Hashing techniques topic in division Indexing and Hashing of Database Management
Answer» The correct choice is (a) All KEYS hash to same index Easiest EXPLANATION - If all keys hash to the same location then the i-th inserted KEY WOULD need i lookups to be found. The probability of looking up i-th key is 1/n (since it’s random). If you KNOW some probability it’s trivial to show that such lookups have linear time.

Discussion

5.	A tablespace is further broken down into ________(a) Tablespace(b) Segments(c) Extents(d) BlocksThis question was posed to me in unit test.The origin of the question is Bitmap Indices topic in chapter Indexing and Hashing of Database Management
Answer» Correct answer is (b) Segments To explain: SEGMENT names are USED in create table and create index commands to PLACE tables or INDEXES on specific DATABASE devices.

Discussion

6.	Bitmap indices are a specialized type of index designed for easy querying on ___________(a) Bit values(b) Binary digits(c) Multiple keys(d) Single keysI had been asked this question during an interview for a job.My question is based upon Bitmap Indices in division Indexing and Hashing of Database Management
Answer» The correct OPTION is (c) MULTIPLE keys The BEST I can explain: Each bitmap INDEX is built on a single key.

Discussion

7.	What is the main limitation of Hierarchical Databases?(a) Limited capacity (unable to hold much data)(b) Limited flexibility in accessing data(c) Overhead associated with maintaining indexes(d) The performance of the database is poorThis question was addressed to me in an online interview.The question is from Ordered Indexing and Hashing topic in portion Indexing and Hashing of Database Management
Answer» Correct choice is (b) LIMITED flexibility in accessing data Easy explanation - In this, the data items are PLACED in a TREE like hierarchical structure.

Discussion

8.	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 spaceThe question was posed to me during an interview.My doubt stems from Index Definition in SQL topic in chapter Indexing and Hashing of Database Management
Answer» Right answer is (b) YES, Indexes are STORED on disk To EXPLAIN: Indexes take MEMORY SLOTS which are located on the disk.

Discussion

9.	The association role defines:(a) How tables are related in the database(b) The relationship between the class diagram and the tables in the database(c) The tables that each attribute is contained(d) Which attribute is the table’s primary keyI have been asked this question in a national level competition.The question is from Ordered Indexing and Hashing in chapter Indexing and Hashing of Database Management
Answer» Right answer is (a) How tables are related in the database The BEST explanation: The tables are ALWAYS related in the database to FORM CONSISTENCY.

Discussion

10.	If an index is _________________ the metadata and statistics continue to exists(a) Disabling(b) Dropping(c) Altering(d) Both Disabling and DroppingThe question was asked by my school principal while I was bunking the class.The above asked question is from Index Definition in SQL in portion Indexing and Hashing of Database Management
Answer» Right answer is (a) Disabling The best 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.

Discussion

11.	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 mentionedThe question was posed to me in quiz.Question is taken from Index Definition in SQL topic in division Indexing and Hashing of Database Management
Answer» The correct answer is (b) Clustered index is built by DEFAULT on unique key columns The best 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.

Discussion

12.	How many types of indexes are there in sql server?(a) 1(b) 2(c) 3(d) 4The question was asked by my college professor while I was bunking the class.Query is from Index Definition in SQL topic in chapter Indexing and Hashing of Database Management
Answer» The correct option is (B) 2 To EXPLAIN: They are clustered INDEX and non clustered index.

Discussion

13.	In ordered indices the file containing the records is sequentially ordered, a ___________ is an index whose search key also defines the sequential order of the file.(a) Clustered index(b) Structured index(c) Unstructured index(d) Nonclustered indexThe question was asked by my school principal while I was bunking the class.The query is from Bitmap Indices in section Indexing and Hashing of Database Management
Answer» Right answer is (a) Clustered index The best I can EXPLAIN: Clustering index are ALSO CALLED primary indices; the term primary index may appear to denote an index on a primary key, but such indices can in fact be built on any SEARCH key.

Discussion

14.	The database design that consists of multiple tables that are linked together through matching data stored in each table is called(a) Hierarchical database(b) Network database(c) Object oriented database(d) Relational databaseI got this question in an online interview.My enquiry is from Ordered Indexing and Hashing in division Indexing and Hashing of Database Management
Answer» The correct choice is (d) Relational database To EXPLAIN: A relational database is a collection of DATA items ORGANIZED as a SET of formally described tables from which data can be accessed or reassembled.

Discussion

15.	In the client / server model, the database:(a) Is downloaded to the client upon request(b) Is shared by both the client and server(c) Resides on the client side(d) Resides on the server sideI have been asked this question at a job interview.This interesting question is from Ordered Indexing and Hashing topic in chapter Indexing and Hashing of Database Management
Answer» Right OPTION is (d) Resides on the server side To explain: The server has all the DATABASE INFORMATION and the client access it.

Discussion

16.	In a __________ index, an index entry appears for only some of the search-key values.(a) Dense(b) Sparse(c) Straight(d) ContinuousThe question was asked in an online quiz.This intriguing question originated from Ordered Indices in portion Indexing and Hashing of Database Management
Answer» CORRECT OPTION is (a) Dense Explanation: Sparse indices can be used only if the relation is stored in SORTED order of the SEARCH KEY, that is if the index is a clustering index.

Discussion

17.	The separation of the data definition from the program is known as:(a) Data dictionary(b) Data independence(c) Data integrity(d) Referential integrityI have been asked this question in examination.My question is from Ordered Indexing and Hashing topic in portion Indexing and Hashing of Database Management
Answer» Right option is (b) DATA independence Explanation: Data DICTIONARY is the PLACE where the MEANING of the data are ORGANIZED.

Discussion

18.	In a B+-tree index ______ for each value, we would normally maintain a list of all records with that value for the indexed attribute.(a) Leaf(b) Node(c) Root(d) LinkI got this question during an online exam.The doubt is from Bitmap Indices in portion Indexing and Hashing of Database Management
Answer» RIGHT CHOICE is (a) Leaf The explanation is: BITMAPS are COMBINED and stored in a B+ tree.

Discussion

19.	A(n) _________ can be used to preserve the integrity of a document or a message.(a) Message digest(b) Message summary(c) Encrypted message(d) None of the mentionedI have been asked this question in an interview.My doubt stems from Ordered Indexing and Hashing topic in division Indexing and Hashing of Database Management
Answer» The correct CHOICE is (c) Encrypted message The BEST I can explain: Encryption algorithms are USED to keep the CONTENTS safe.

Discussion

20.	The goal of hashing is to produce a search that takes(a) O(1) time(b) O(n2 )time(c) O(log n ) time(d) O(n log n ) timeThis question was posed to me in a job interview.The query is from Hashing techniques in portion Indexing and Hashing of Database Management
Answer» RIGHT choice is (a) O(1) time The EXPLANATION is: Time complexity is given by the big oh NOTATION.

Discussion

21.	A technique for direct search is(a) Binary Search(b) Linear Search(c) Tree Search(d) HashingThis question was posed to me in an interview for job.Question is taken from Hashing techniques in portion Indexing and Hashing of Database Management
Answer» Right answer is (d) Hashing For explanation: Hashing is one way to enable SECURITY during the process of MESSAGE TRANSMISSION when the message is intended for a particular RECIPIENT only.

Discussion

22.	A hash table can store a maximum of 10 records, currently there are records in location 1, 3,4,7,8,9,10. The probability of a new record going into location 2, with hash functions resolving collisions by linear probing is(a) 0.1(b) 0.6(c) 0.2(d) 0.5This question was addressed to me in an international level competition.This key question is from Hashing techniques in chapter Indexing and Hashing of Database Management
Answer» Right option is (b) 0.6 The best EXPLANATION: Hashing is used to index and retrieve items in a database because it is easier to find the item using the SHORTENED hashed KEY than using the ORIGINAL value.

Discussion

23.	A _______ on the attribute A of relation r consists of one bitmap for each value that A can take.(a) Bitmap index(b) Bitmap(c) Index(d) ArrayThe question was asked in quiz.I'd like to ask this question from Bitmap Indices topic in chapter Indexing and Hashing of Database Management
Answer» RIGHT ANSWER is (a) Bitmap index The explanation is: A bitmap is SIMPLY an array of BITS.

Discussion

24.	The property (or set of properties) that uniquely defines each row in a table is called the:(a) Identifier(b) Index(c) Primary key(d) Symmetric keyThis question was addressed to me during an interview.My doubt is from Ordered Indexing and Hashing in chapter Indexing and Hashing of Database Management
Answer» RIGHT CHOICE is (c) PRIMARY key The best I can EXPLAIN: Primary is used to uniquely identify the tuples.

Discussion

25.	Insertion of a large number of entries at a time into an index is referred to as __________ of the index.(a) Loading(b) Bulk insertion(c) Bulk loading(d) Increase insertionThis question was addressed to me during an interview.My doubt is from Ordered Indices in division Indexing and Hashing of Database Management
Answer» RIGHT OPTION is (c) BULK loading To explain: Bulk loading is USED to improve efficiency and SCALABILITY.

Discussion

26.	In B+ tree the node which points to another node is called(a) Leaf node(b) External node(c) Final node(d) Internal nodeI got this question in class test.This intriguing question comes from Ordered Indices in chapter Indexing and Hashing of Database Management
Answer» CORRECT OPTION is (d) Internal node The EXPLANATION is: Nonleaf NODES are also referred to as internal nodes.

Discussion

27.	In a _______ clustering index, the index record contains the search-key value and a pointer to the first data record with that search-key value and the rest of the records will be in the sequential pointers.(a) Dense(b) Sparse(c) Straight(d) ContinuousThis question was addressed to me in an online quiz.Query is from Ordered Indices in chapter Indexing and Hashing of Database Management
Answer» The correct ANSWER is (a) DENSE Easiest explanation - In a dense nonclustering index, the index must store a LIST of pointers to all records with the same search-key value.

Discussion

28.	An ____________ consists of a search-key value and pointers to one or more records with that value as their search-key value.(a) Index entry(b) Index hash(c) Index cluster(d) Index mapThe question was posed to me in unit test.My question comes from Ordered Indices in division Indexing and Hashing of Database Management
Answer» CORRECT answer is (a) Index entry The explanation is: The pointer to a RECORD consists of the identifier of a DISK BLOCK and an OFFSET within the disk block to identify the record within the block.

Discussion

29.	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 mentionedThe question was posed to me in an interview.I'd like to ask this question from Index Definition in SQL in section Indexing and Hashing of Database Management
Answer» The correct answer is (b) A COMPOSITE INDEX is a combination of index on 2 or more columns Easiest EXPLANATION - A composite index is an index on TWO or more columns of a table.

Discussion

30.	Bitmaps can be used as a compressed storage mechanism at the leaf nodes of ________ for those values that occur very frequently.(a) B-trees(b) B+-trees(c) Bit trees(d) Both B-trees and B+-treesI have been asked this question in a job interview.My question is taken from Bitmap Indices in division Indexing and Hashing of Database Management
Answer» The CORRECT CHOICE is (b) B+-trees The explanation is: BITMAPS are COMBINED and stored in a B+ tree.

Discussion

31.	Consider a hash table of size seven, with starting index zero, and a hash function (3x + 4)mod7. Assuming the hash table is initially empty, which of the following is the contents of the table when the sequence 1, 3, 8, 10 is inserted into the table using closed hashing? Note that ‘_’ denotes an empty location in the table.(a) 8, _, _, _, _, _, 10(b) 1, 8, 10, _, _, _, 3(c) 1, _, _, _, _, _,3(d) 1, 10, 8, _, _, _, 3I got this question in an online interview.This question is from Hashing techniques in chapter Indexing and Hashing of Database Management
Answer» The correct choice is (b) 1, 8, 10, _, _, _, 3 For EXPLANATION: A FORMULA generates the hash, which helps to PROTECT the security of the transmission from unauthorized users.

Discussion

32.	If h is any hashing function and is used to hash n keys in to a table of size m, where n
Answer» Right choice is (a) Less than 1 Easy explanation - Hashing is ALSO a method of SORTING key values in a DATABASE table in an EFFICIENT MANNER.

Discussion

33.	A search key containing more than one attribute is referred to as a _________ search key.(a) Simple(b) Composite(c) Compound(d) SecondaryThe question was asked in an internship interview.My query is from Ordered Indices in portion Indexing and Hashing of Database Management
Answer» Right OPTION is (b) Composite Easiest EXPLANATION - The structure of the INDEX is the same as that of any other index, the only difference being that the search key is not a SINGLE attribute, but RATHER is a list of attributes.

Discussion

34.	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 mentionedI got this question in semester exam.My query is from Index Definition in SQL in chapter Indexing and Hashing of Database Management
Answer» Correct option is (B) It makes harder for sql SERVER engines to work to work on index which have LARGE keys The best I can explain: INDEXES tend to improve the performance.

Discussion

35.	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 mentionedThe question was asked in my homework.I'd like to ask this question from Index Definition in SQL topic in section Indexing and Hashing of Database Management
Answer» RIGHT choice is (c) It is used for pointing data rows containing key values Best 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.

Discussion

36.	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 mentionedI had been asked this question by my college professor while I was bunking the class.Asked question is from Index Definition in SQL topic in chapter Indexing and Hashing of Database Management
Answer» The correct answer is (d) All of the mentioned The BEST 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.

Discussion

37.	The searching technique that takes O (1) time to find a data is(a) Linear Search(b) Binary Search(c) Hashing(d) Tree SearchThis question was addressed to me in an internship interview.Question is taken from Hashing techniques in chapter Indexing and Hashing of Database Management
Answer» Correct choice is (c) Hashing To explain: A formula GENERATES the HASH, which helps to PROTECT the security of the transmission from UNAUTHORIZED users.

Discussion

38.	Bitmaps can be combined with regular B+-tree indices for relations where a few attribute values are extremely common, and other values also occur, but much less frequently.(a) Bitmap, B-tree(b) Bitmap, B+tree(c) B-tree, Bitmap(d) B+tree, BitmapThe question was posed to me during a job interview.Question is taken from Bitmap Indices in section Indexing and Hashing of Database Management
Answer» Correct option is (b) BITMAP, B+tree To EXPLAIN: Bitmaps are COMBINED and STORED in a B+ tree.

Discussion

39.	Indices whose search key specifies an order different from the sequential order of the file are called ___________ indices.(a) Nonclustered(b) Secondary(c) All of the mentioned(d) None of the mentionedI have been asked this question in an interview for job.Origin of the question is Ordered Indices topic in division Indexing and Hashing of Database Management
Answer» Correct ANSWER is (c) All of the mentioned To explain: Nonclustering index is also CALLED SECONDARY indices.

Discussion

40.	To identify the deleted records we use the ______________(a) Existence bitmap(b) Current bitmap(c) Final bitmap(d) Deleted bitmapThis question was posed to me during an internship interview.My question is based upon Bitmap Indices in chapter Indexing and Hashing of Database Management
Answer» Right option is (a) Existence bitmap To explain: The bitmaps which are DELETED are DENOTED by 0.

Discussion

41.	The traditional storage of data that is organized by customer, stored in separate folders in filing cabinets is an example of what type of ‘database’ system?(a) Hierarchical(b) Network(c) Object oriented(d) RelationalI have been asked this question in a job interview.My question is based upon Ordered Indexing and Hashing in portion Indexing and Hashing of Database Management
Answer» Correct ANSWER is (a) Hierarchical The BEST I can explain: Hierarchy is based on Parent-Child Relationship. Parent-Child Relationship TYPE is basically 1:N relationship.

Discussion

42.	What is the best definition of a collision in a hash table?(a) Two entries are identical except for their keys(b) Two entries with different data have the exact same key(c) Two entries with different keys have the same exact hash value(d) Two entries with the exact same key have different hash valuesI got this question during an online interview.This key question is from Hashing techniques in division Indexing and Hashing of Database Management
Answer» Correct answer is (a) TWO entries are identical EXCEPT for their keys Best EXPLANATION: This level is the root of the tree.

Discussion

43.	Key value pairs is usually seen in(a) Hash tables(b) Heaps(c) Both Hash tables and Heaps(d) Skip listThe question was posed to me in a job interview.This intriguing question originated from Hashing techniques topic in chapter Indexing and Hashing of Database Management
Answer» Correct option is (a) Hash tables Best explanation: Hashing is USED to INDEX and retrieve ITEMS in a database because it is EASIER to find the item using the shortened HASHED key than using the original value.

Discussion

44.	In ordered indices the file containing the records is sequentially ordered, a ___________ is an index whose search key also defines the sequential order of the file.(a) Clustered index(b) Structured index(c) Unstructured index(d) Nonclustered indexThis question was addressed to me in my homework.This is a very interesting question from Ordered Indices topic in portion Indexing and Hashing of Database Management
Answer» Right answer is (a) Clustered INDEX The best explanation: Clustering index are ALSO called PRIMARY indices; the term primary index may appear to denote an index on a primary KEY, but such indices can in FACT be built on any search key.

Discussion

Explore topic-wise InterviewSolutions in .

A hash function must meet ________ criteria.(a) Two(b) Three(c) Four(d) None of the mentionedI got this question during an online interview.My question comes from Ordered Indexing and Hashing topic in section Indexing and Hashing of Database Management

A tablespace is further broken down into ________(a) Tablespace(b) Segments(c) Extents(d) BlocksThis question was posed to me in unit test.The origin of the question is Bitmap Indices topic in chapter Indexing and Hashing of Database Management

How many types of indexes are there in sql server?(a) 1(b) 2(c) 3(d) 4The question was asked by my college professor while I was bunking the class.Query is from Index Definition in SQL topic in chapter Indexing and Hashing of Database Management

In a __________ index, an index entry appears for only some of the search-key values.(a) Dense(b) Sparse(c) Straight(d) ContinuousThe question was asked in an online quiz.This intriguing question originated from Ordered Indices in portion Indexing and Hashing of Database Management

In a B+-tree index ______ for each value, we would normally maintain a list of all records with that value for the indexed attribute.(a) Leaf(b) Node(c) Root(d) LinkI got this question during an online exam.The doubt is from Bitmap Indices in portion Indexing and Hashing of Database Management

The goal of hashing is to produce a search that takes(a) O(1) time(b) O(n2 )time(c) O(log n ) time(d) O(n log n ) timeThis question was posed to me in a job interview.The query is from Hashing techniques in portion Indexing and Hashing of Database Management

A technique for direct search is(a) Binary Search(b) Linear Search(c) Tree Search(d) HashingThis question was posed to me in an interview for job.Question is taken from Hashing techniques in portion Indexing and Hashing of Database Management

A _______ on the attribute A of relation r consists of one bitmap for each value that A can take.(a) Bitmap index(b) Bitmap(c) Index(d) ArrayThe question was asked in quiz.I'd like to ask this question from Bitmap Indices topic in chapter Indexing and Hashing of Database Management

In B+ tree the node which points to another node is called(a) Leaf node(b) External node(c) Final node(d) Internal nodeI got this question in class test.This intriguing question comes from Ordered Indices in chapter Indexing and Hashing of Database Management

If h is any hashing function and is used to hash n keys in to a table of size m, where n

A search key containing more than one attribute is referred to as a _________ search key.(a) Simple(b) Composite(c) Compound(d) SecondaryThe question was asked in an internship interview.My query is from Ordered Indices in portion Indexing and Hashing of Database Management

The searching technique that takes O (1) time to find a data is(a) Linear Search(b) Binary Search(c) Hashing(d) Tree SearchThis question was addressed to me in an internship interview.Question is taken from Hashing techniques in chapter Indexing and Hashing of Database Management

To identify the deleted records we use the ______________(a) Existence bitmap(b) Current bitmap(c) Final bitmap(d) Deleted bitmapThis question was posed to me during an internship interview.My question is based upon Bitmap Indices in chapter Indexing and Hashing of Database Management

Key value pairs is usually seen in(a) Hash tables(b) Heaps(c) Both Hash tables and Heaps(d) Skip listThe question was posed to me in a job interview.This intriguing question originated from Hashing techniques topic in chapter Indexing and Hashing of Database Management