Why transactions ensure data consistency in DBMS Theory - Challenge Your Understanding

Challenge - 5 Problems

🧠 Conceptual

intermediate

What is the main property of transactions that ensures data consistency?

Which property of a database transaction guarantees that data remains consistent even if a failure occurs during the transaction?

A Atomicity

B Isolation

C Durability

D Concurrency

💡 Hint

Think about the all-or-nothing nature of transactions.

Atomicity means a transaction is completed fully or not at all, preventing partial updates that could corrupt data.

📋 Factual

intermediate

Which ACID property prevents interference between concurrent transactions?

Which property of transactions ensures that concurrent transactions do not affect each other's execution, helping maintain data consistency?

A Durability

B Atomicity

C Isolation

D Consistency

💡 Hint

Consider how transactions appear to run one after another even if they run at the same time.

Isolation ensures that transactions are executed independently without interference, preserving data correctness.

🚀 Application

advanced

What happens if a transaction fails halfway through?

Consider a bank transfer transaction that debits one account and credits another. If the system crashes after debiting but before crediting, what ensures data consistency?

A The transaction rolls back, undoing the debit to keep data consistent.

B The transaction is partially saved, causing inconsistent data.

C The system ignores the failure and continues processing.

D The credit is applied twice to compensate.

💡 Hint

Think about how transactions handle partial failures.

Rollback undoes all changes if a transaction fails, so no partial updates remain, keeping data consistent.

🔍 Analysis

advanced

How does durability contribute to data consistency after a crash?

After a power failure, how does the durability property of transactions help maintain consistent data?

A It prevents any transactions from starting during a crash.

B It automatically deletes uncommitted data to free space.

C It allows partial transactions to be saved for later completion.

D It ensures all committed transactions are saved permanently and not lost.

💡 Hint

Think about what happens to committed data after a system failure.

Durability guarantees that once a transaction commits, its changes are saved permanently, so data remains consistent after crashes.

❓ Reasoning

expert

Why is the consistency property dependent on other ACID properties?

Explain why the consistency property in transactions relies on atomicity, isolation, and durability to maintain database correctness.

A Because consistency is unrelated to atomicity, isolation, or durability.

B Because consistency alone cannot prevent partial updates, interference, or data loss without the other properties.

C Because consistency only applies to read operations, not writes.

D Because consistency automatically fixes errors caused by other properties failing.

💡 Hint

Consider how each ACID property supports the overall correctness of data.

Consistency depends on atomicity to avoid partial changes, isolation to prevent interference, and durability to save committed data, all ensuring correct data.