Context

A supply chain platform such as FleetCart processes many inventory updates, shipment events, and order transactions at the same time. In this kind of system, database correctness matters as much as speed.

Core question

Explain what ACID means in a relational database and why it matters in a high-transaction supply chain system. Your answer should cover:

1. What each property — Atomicity, Consistency, Isolation, Durability — means
2. What can go wrong if one of these properties is weak or missing
3. Practical examples involving inventory allocation, order creation, payment capture, or shipment updates
4. How transactions in PostgreSQL help enforce these guarantees

Scope guidance

The interviewer is looking for a clear conceptual explanation, not a long theory lecture. Define each ACID property in simple terms, connect it to real operational risks like overselling stock or partial updates, and mention how transaction boundaries, commits, rollbacks, and concurrent access affect system reliability.