What are the ACID properties of a database and why do they matter?

SQL
Medium
Flipkart
109.9K views

This DBMS question tests your knowledge of transaction guarantees essential for reliable data storage.

Why Interviewers Ask This

ACID properties ensure data integrity during transactions, which is non-negotiable for financial applications like e-commerce. Interviewers want to confirm you understand atomicity, consistency, isolation, and durability. This shows you can design systems that prevent data loss or corruption during failures.

How to Answer This Question

List each property with a brief definition. Provide a concrete example, such as a money transfer, to illustrate all four. Explain how violations would lead to incorrect balances or lost orders. Emphasize the trade-offs involved in enforcing these properties.

Key Points to Cover

  • Atomicity definition
  • Consistency rules
  • Isolation levels
  • Durability guarantee

Sample Answer

ACID stands for Atomicity, Consistency, Isolation, and Durability. Atomicity ensures a transaction is all-or-nothing. Consistency maintains valid database states. Isolation prevents concurrent transactions from interfering. Durability guarantees committed changes persist even after crashes. For Flipkart, if a payment fails halfway, atomicity ensures the order isn't created, preserving accurate inventory and financial records.

Common Mistakes to Avoid

  • Defining terms without examples
  • Confusing isolation with consistency
  • Ignoring crash scenarios

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