IT. Data Base Management System -Final Exam

Question 10

IT. Data Base Management System -Final Exam. Which method retrieves every record and checks conditions?

• A. Linear search using brute force technique
• B. Binary search using sorted file structure
• C. Hash search using direct key mapping
• D. Index search using primary key access

Question 11

What does ‘seek time’ (s) represent in the context of disk access?

• A. The time it takes for the disk to spin to the correct sector
• B. The time spent calculating a hash function
• C. The time required for the read-write head to move to the correct track
• D. The time taken to transfer data to main memory

Question 12

T1 updates balance to $200 but has not committed. T2 reads $200 and uses it. Then T1 aborts and the balance reverts to $150. T2 acted on a value that never officially existed. This is called:

• A. A Serializable violation
• B. A Phantom Read
• C. A Non-repeatable Read
• D. A Temporary Update (Dirty Read)

Question 13

The Primary Copy technique differs from the Primary Site technique in that:

• A. Instead of one site managing all locks, each data item has a designated primary copy, and locking that copy is sufficient — spreading the load across sites
• B. Primary Copy replicates every item to all sites
• C. Primary Copy requires unanimous agreement from all sites for every lock
• D. Primary Copy uses no locks at all

Question 14

What kind of data does a ‘Spatial Database’ manage

• A. Location-based data such as maps, coordinates, and geographic information
• B. Text documents and emails
• C. Audio and video files only
• D. Financial transactions between banks

Question 15

What is the main goal of RAID technology in database systems?

• A. To reduce the physical size of disk packs
• B. To replace magnetic disks with solid-state drives
• C. To even out performance gaps between disks and microprocessors while providing redundancy
• D. To eliminate the need for file headers

Question 16

In distributed query processing, the Semijoin technique helps by:

• A. Sending only the join-attribute values to the other site first, reducing the number of rows transferred before the full join
• B. Caching the most recent query result
• C. Splitting the join into two independent queries
• D. Performing the entire join at a single central site

Question 17

In a B+-Tree, where are the actual data pointers (or records) stored?

• A. Only in the root node
• B. In every internal node and the leaf nodes
• C. Only in the leaf nodes
• D. Distributed randomly across all levels IT. Data Base Management System -Final Exam

Question 18

In voting-based concurrency control, a transaction acquires a lock on a data item when:

• A. The transaction has been waiting for more than 30 seconds
• B. A majority of sites holding a copy of that item grant the lock request
• C. The primary site grants the lock
• D. All sites unanimously grant the lock request

Question 19

The ‘No-Force’ policy means that ______

• A. Data must be written to disk immediately
• B. Transactions cannot be aborted
• C. Updated pages do not need to be written to disk at the time of commit
• D. Users are not forced to use passwords

Question 20

What does the ‘WITH GRANT OPTION’ clause allow a user to do?

• A. Update any table in the database
• B. Bypass encryption protocols
• C. Revoke privileges from the database administrator
• D. Pass the granted privilege on to other users

Question 21

A larger timestamp value indicates:

• A. Older transaction always
• B. Invalid transaction state
• C. Lower priority transaction
• D. More recent transaction or operation

Question 22

In the query processing pipeline, which component is responsible for producing the execution plan?

• A. Query code generator
• B. Scanning, parsing, and validating
• C. Runtime database processor
• D. Query optimizer

Question 23

A query tree is a tree structure whose nodes denote ______ operations.

• A. Relational calculus
• B. Relational algebra
• C. SQL commands
• D. Database catalog records

Here is the full transcription of your exam questions with the correct answers clearly highlighted.

Question 23

How is ‘Clustering’ different from ‘Classification’?

• A: Clustering groups data into categories WITHOUT predefined labels — the algorithm discovers the groups on its own
• B: Clustering requires more storage than classification
• C: Clustering is faster but less accurate
• D: Clustering only works with text data

Question 24

What is Horizontal Fragmentation?

• A: Splitting a table by selecting certain rows (tuples) based on a condition
• B: Phantom reads in a single-site query
• C: Splitting a table by selecting certain columns
• D: Copying the entire table to all sites

Question 25

Two-phase locking consists of:

• A: Execution and commit phases
• B: Growing and shrinking phases
• C: Locking and unlocking phases
• D: Read and write phases

Question 26

Deadlock detection involves:

• A: Restarting all transactions always
• B: Preventing locks entirely
• C: Finding cycles in wait-for graph
• D: Ignoring blocked transactions

Question 27

An employee’s record shows Salary = 8000 with ValidStart = 2022-01-01 and ValidEnd = 2023-12-31. What does ‘Valid Time’ represent?

• A: When the salary record was physically inserted into the database
• B: The period during which the salary of 8000 was true in the real world
• C: The timestamp when the last query on this record was run
• D: The system time when a backup was taken

Question 28

On which operation can binary search be effectively used?

• A: σSSN=’123456789’​(EMPLOYEE)
• B: σDNO=5​(EMPLOYEE)
• C: σDNO=5 AND SALARY>30000 AND SEX=’F’​(EMPLOYEE)
• D: σDNUMBER>5​(DEPARTMENT)

Question 29

A concurrent schedule is called serializable if:

• A: The precedence graph contains at least one cycle
• B: It produces the same final database state as some serial execution of the same transactions
• C: Every transaction commits within 1 second
• D: All transactions run one at a time with no overlap

Question 30

In SQL, which command is used to provide a user with specific privileges on a table?

• A: PROVIDE
• B: ALLOW
• C: ASSIGN
• D: GRANT

Question 31

A well-formed transaction must:

• A: Access data without locks
• B: Unlock before locking items
• C: Ignore lock compatibility rules
• D: Lock data before accessing it

Question 32

Which RAID level uses mirrored disks to provide the highest reliability for data?

• A: RAID level 0
• B: RAID level 5
• C: RAID level 1
• D: RAID level 3

Question 33

A secondary index is typically used on fields that are _

• A: The primary ordering key of the file
• B: Only used for aggregate functions
• C: Already physically ordered
• D: Non-ordering fields

Question 34

A Bitemporal Database tracks two-time dimensions. What are they?

• A: Start time and End time of a single time period IT. Data Base Management System -Final Exam
• B: System time and user-defined time
• C: Valid Time (when the fact was true in reality) and Transaction Time (when it was recorded in the database)
• D: Creation time and deletion time of a row

Question 35

The star (*) Property in the Bell-LaPadula model prevents a subject from _________

• A: Accessing the database without a password
• B: Granting privileges to other subjects
• C: Reading data at a higher security level
• D: Writing data to a lower security level

Question 36

Wait-for graph is used for:

• A: Managing disk storage allocation
• B: Improving indexing efficiency
• C: Detecting deadlocks in transactions
• D: Scheduling backup operations

Question 37

In a Client-Server database architecture, a client receives a user’s SQL query and decomposes it into sub-queries. What happens next?

• A: Sub-queries are discarded and the client reformulates one simpler query
• B: The client forwards the entire original query to a single master server
• C: Each sub-query is sent to the appropriate server; each server processes its part and returns the result; the client combines all results
• D: The client executes all sub-queries locally using its own data store

Question 38

Lock upgrade means:

• A: Converting read lock to write lock
• B: Releasing a lock early
• C: Converting write lock to read lock
• D: Changing lock manager data structures

Question 39

What is a Multimedia Database Management System?

• A: A database system designed exclusively for mobile devices and touchscreen interfaces
• B: A database that stores text data only and does not support indexing
• C: A database that can store and manage different types of media such as images, audio, video, and text
• D: A database that uses rows and columns to store relational tabular data only

Question 40

Which of the following is a drawback of the Primary Site technique for concurrency control in distributed databases?

• A: It requires data replication at all sites
• B: If the primary site fails, the entire distributed database becomes inaccessible until a new primary is elected
• C: It cannot handle simple transactions
• D: It is more expensive than full replication

Question 41

Which of the following describes an “Unrepeatable Read” anomaly?

• A: The transaction read a data item that was changed by another transaction, which then rolled back
• B: The transaction read the data item, then another transaction changed the data item and committed, and then the first transaction re-read the data item and found a different value
• C: The transaction read a set of rows satisfying a condition, then another transaction inserted a new row satisfying the same condition
• D: Two transactions write the same data item, and the second write overwrites the first write

Here is the transcribed compilation of your exam questions with the correct answers clearly highlighted.

Question 41

The system log records [write, T1, X, 50, 80]. During recovery after a crash, what do the values 50 and 80 represent?

• A. 50 is the old (before) value of X; 80 is the new (after) value of X
• B. 50 is the commit time; 80 is the rollback time
• C. 50 is the block number; 80 is the record size
• D. 50 is the new value; 80 is the transaction ID

Question 42

Which security mechanism is based on the granting and revoking of privileges to users?

• A. Mandatory Access Control (MAC)
• B. Discretionary Access Control (DAC)
• C. Statistical Control
• D. Flow Control

Question 43

What is a ‘Temporal Database’?

• A. A database used only for scheduling meetings
• B. A database that keeps track of data changes over time, storing historical versions of data
• C. A database that stores data only for one hour
• D. A very fast database stored in RAM\

Question 44

Which of the following is a physical database design decision related to indexing?

• A. Which view definition language to use
• B. Whether to use a hash index over a tree index
• C. Whether to normalize the database to BCNF
• D. How to partition data across different physical disks for backup

Question 45

Validation-based concurrency control is:

• A. Optimistic concurrency control scheme
• B. Timestamp ordering method
• C. Lock-based pessimistic method
• D. Deadlock prevention technique

Question 46

Which of the following is an example of fine granularity locking?

• A. A single attribute of a tuple
• B. A disk block
• C. The entire database IT. Data Base Management System -Final Exam
• D. An entire file

Question 47

Which recovery method maintains two page tables to avoid the use of a log for recovery?

• A. Immediate Update
• B. Deferred Update
• C. Shadow Paging
• D. ARIES

Question 48

Lock downgrade means:

• A. Converting read lock to write lock
• B. Converting write lock to read lock
• C. Removing lock permanently
• D. Locking multiple items together

Question 49

In an unordered (heap) file, what is the average number of block accesses required to search for a specific record?

• A. b/2
• B. $\log_2 b$
• C. b
• D. 1

Question 50

In Multiple Granularity Locking, what does a Shared-Intention-Exclusive (SIX) lock indicate?

• A. The transaction has released all locks
• B. The current node is locked in shared mode, but an exclusive lock will be requested on some descendant node(s)
• C. No locks will be requested on descendant nodes
• D. The current node is locked in exclusive mode only

Question 51

Based Access Control (RBAC) is primarily used to ___________

• A. Manage physical disk blocks
• B. Link privileges to job functions instead of individual users
• C. Encrypt data at rest
• D. Prevent SQL injection attacks

Question 52

Thomas’s write rule allows:

• A. Converting writes to reads
• B. Rejecting all write operations
• C. Locking all data items
• D. Ignoring outdated write operations

Question 53

Which option is recommended to tune a database when a query contains multiple selection conditions connected via OR and fails to use an index?

• A. Replace the OR conditions with AND conditions
• B. Convert the query into a correlated subquery
• C. Remove all indexes from the tables to force a different execution plan
• D. Split the query into a UNION of queries, each with a condition on an attribute that causes an index to be used

Question 54

What is the main heuristic in query optimization?

• A. Apply indexing operations during query execution
• B. Apply operations that reduce intermediate result sizes first
• C. Apply projection operations after join operations
• D. Apply join operations before selection operations

Question 55

The “steal” policy allows:

• A. A dirty page to be written to disk before a transaction commits
• B. A transaction to read uncommitted changes
• C. The log to be written to disk after the transaction commits
• D. Replicating data to a secondary database instance without permission

Question 56

Basic 2PL protocol can cause:

• A. Low concurrency
• B. Loss of data integrity
• C. Infinite loops during execution
• D. Deadlocks during execution

Question 57

The main objective of a checkpoint mechanism is to:

• A. Reduce the amount of log to be processed during recovery
• B. Optimize the join execution plan
• C. Encrypt the database log files
• D. Restrict access to specific records

Question 58

Which phase of the ARIES recovery algorithm is responsible for repeating history?

• A. Abort Phase
• B. Undo Phase
• C. Analysis Phase
• D. Redo Phase

Question 59

In a strict schedule, a transaction T can read or write a data item X modified by another transaction T:

• A. Immediately after the modification
• B. Only after T has committed or aborted IT. Data Base Management System -Final Exam
• C. Only after T enters its shrinking phase
• D. Concurrent with T’s active execution

Question 60

In a cascadeless schedule:

• A. A transaction can read a data item modified by an uncommitted transaction
• B. A transaction can write a data item modified by an uncommitted transaction
• C. Transactions are prevented from aborting during execution
• D. A transaction can read a data item only after it is committed