ELEVATE SKILLS!
Q: 1 Database failure may occur due to which of the following?
Transaction failure
System crash
Disk failure
All of the above
[ Option D ]
Database failures can occur for various reasons:
Q: 2 Which of the following is not a database recovery technique?
Log Based
Shadow Paging
Check- Points
Hashing
[ Option D ]
Database recovery techniques are used to restore the database to a consistent state after a failure.
Hashing is a data organization and access technique used for fast searching.
Q: 3 Correct order of applying 3 passes in ARIES recovery algorithm is—
Undo, Analysis, Redo
Analysis, Redo, Undo
Undo, Redo, Analysis
Analysis, Undo, Redo
[ Option B ]
ARIES stands for Algorithms for Recovery and Isolation Exploiting Semantics. It is a robust and widely-used database recovery algorithm designed to ensure data integrity and consistency in the event of system failures or crashes.
ARIES is based on the Write-Ahead Logging (WAL) protocol, which guarantees that any changes to the database are first recorded in a log before being applied to the database itself.
The correct order of applying the three passes in the ARIES recovery algorithm is Analysis, Redo, Undo.
| PHASE | PURPOSE | DESCRIPTION |
|---|---|---|
| Analysis | Determines the state of the system at crash time. | Starts from the latest checkpoint and scans forward to reconstruct active transactions and dirty pages. Identifies the starting point for redo. |
| Redo | Reapplies all modifications to ensure durability. | Repeats history by redoing all updates from the log starting at the earliest dirty page until the crash, bringing the database to the exact pre-crash state. |
| Undo | Rolls back incomplete transactions. | Scans the log backward to undo the effects of uncommitted or aborted transactions to maintain atomicity and consistency. |
Q: 4 Which of the following control measures is not corresponding to database security?
Access control
Interface control
Flow control
Data encryption
[ Option B ]
Database Security refers to protecting data from unauthorized access, misuse, or corruption. To ensure data integrity and privacy, several control measures are implemented within a database system.
| SECURITY MECHANISM | DESCRIPTION |
|---|---|
| Access Control | Restricts user access to database objects based on permissions. Ensures only authorized users can read, insert, update, or delete data. |
| Authentication | Verifies user identity before allowing access, can use passwords, biometrics, or multi-factor authentication. |
| Authorization | Defines user roles and privileges after authentication, ensures users perform only allowed operations. |
| Encryption | Protects data confidentiality by converting it into unreadable format, applies to data at rest and data in transit. |
| Audit Trails / Logging | Records user activities and database operations. Helps detect misuse and ensures accountability. |
| Flow Control | Prevents data from flowing between unauthorized levels or entities. Ensures multilevel security. |
| Backup and Recovery | Maintains copies of data to restore in case of failure or loss. Protects data integrity and availability. |
| Physical Security | Protects hardware and storage from unauthorized access or damage. Ensures overall system security. |
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