Valid properties of a transaction?
Interviewer Expectations for this Question
01
Core Competency
Assesses fundamental understanding of SQL & Databases conventions, runtime behavior, and memory/performance considerations.
02
Evaluation Criteria
Hiring managers look for precision, avoidance of ambiguous jargon, and ability to explain trade-offs under real production conditions.
Comprehensive Model Answer
Verified Solution
The four foundational properties that guarantee database transactions are processed reliably are known as ACID:
- Atomicity: "All or nothing." If any statement within the transaction fails, all changes are rolled back to the initial state.
- Consistency: Transactions transition the database from one valid state to another, strictly obeying all constraints, cascades, and triggers.
- Isolation: Concurrent transactions execute independently without interfering with each other (governed by isolation levels like
READ COMMITTED,REPEATABLE READ, andSERIALIZABLE). - Durability: Once committed, changes are permanently recorded on disk and will not be lost even during system failure.
Candidate Response Strategy & Interview Tips
- Start with a concise one-sentence summary: Deliver a direct, confident answer first before expanding into nuances.
- Demonstrate real-world trade-offs: Discuss where this approach excels and when you would avoid it in production systems.
- Discuss complexity & edge cases: Proactively explain time/space complexity or boundary conditions (null values, scale limits).
- Prepare for interviewer follow-ups: Technical hiring panels frequently probe deeper into concurrency, backward compatibility, or alternative libraries.