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DBMS Log-Based Recovery MCQs
DBMS Log-Based Recovery MCQs: This section contains multiple-choice questions and answers on Log-Based Recovery in DBMS.
Submitted by Anushree Goswami, on April 18, 2022
1. Logs consist of a ___ of records.
- Compilations
- Series
- Data
- Table
Answer: B) Series
Explanation:
Logs consist of a series of records.
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2. In case of any failure, a log of each transaction can be recovered there from some ___ storage.
- Stable
- Unstable
- Recovery
- System
Answer: A) Stable
Explanation:
In case of any failure, a log of each transaction can be recovered there from some stable storage.
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3. ___ is used to keep track of all database operations.
- Dragging
- Logging
- Receiving
- Recovery
Answer: B) Logging
Explanation:
Logging is used to keep track of all database operations.
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4. It is advisable, to store the ___ before applying the actual transaction to the database.
- Data
- Logs
- Receive
- Record
Answer: B) Logs
Explanation:
It is advisable, however, to store the logs before applying the actual transaction to the database.
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5. How many approaches are there to modify the database?
- 2
- 3
- 4
- 5
Answer: A) 2
Explanation:
2 approaches are there to modify the database.
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6. What are the two approaches to modify the database?
- Deferred database modification
- Immediate database modification
- Both A and B
- None of the above
Answer: C) Both A and B
Explanation:
Two approaches to modify the database are -
- Deferred database modification
- Immediate database modification
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7. When ___ modification is applied, the change to the database does not occur until the transaction is committed.
- Deferred
- Immediate
- Both A and B
- None of the above
Answer: A) Deferred
Explanation:
When deferred modification is applied, the change to the database does not occur until the transaction is committed.
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8. All logs are created and stored in ___ storage when the deferred database method is used, and data is synced to the database when a transaction commits.
- Stable
- Unstable
- System
- Recovery
Answer: A) Stable
Explanation:
All logs are created and stored in stable storage when the deferred database method is used, and data is synced to the database when a transaction commits.
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9. Modifications to the database occur while a transaction is still active, using the ___ modification technique.
- Deferred
- Immediate
- Both A and B
- None of the above
Answer: B) Immediate
Explanation:
Modifications to the database occur while a transaction is still active, using the Immediate modification technique.
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10. The ___ is updated immediately after every operation when using the immediate modification technique.
- Table
- Row
- Column
- Database
Answer: D) Database
Explanation:
The database is updated immediately after every operation when using the immediate modification technique.
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11. Once the system crashes, the log is consulted to determine what needs to be un___ and what needs to be re-___.
- Open
- Tie
- Done
- Wrap
Answer: C) Done
Explanation:
Once the system crashes, the log is consulted to determine what needs to be undone and what needs to be re-done.
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12. Log records that contain the records <__, Start> and <__, Commit> or <__, Commit> indicate that the Transaction __ must be rewritten.
- Start
- Commit
- Ti
- None
Answer: C) Ti
Explanation:
Log records that contain the records <Ti, Start> and <Ti, Commit> or <Ti, Commit> indicate that the Transaction Ti must be rewritten.
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13. The Transaction Ti needs to be reversed if the log consists of record <Tn, Begin>, but does not contain record <Ti, Commit> or <Ti, ____>.
- Begin
- End
- Commit
- Abort
Answer: D) Abort
Explanation:
The Transaction Ti needs to be reversed if the log consists of record <Tn, Begin>, but does not contain record <Ti, Commit> or <Ti, Abort>.
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