Inventory Management System

Introduction

Inventory schemas track stock, movements, warehouses with strong consistency to avoid overselling.

Understanding the topic

Core concepts to understand:

• Products + stock per warehouse.
• Movements table (in/out, reasons).
• Reservations during checkout.
• Use SELECT FOR UPDATE to avoid oversell.
• Reorder thresholds with alerts.

Syntax reference

Visual workflow / architecture:

products ──▶ stock(warehouse_id, qty)
                            ▲
movements ─ in/out reason ──┘
reservations ─ TTL hold during checkout

Real-world use

Shopify, Amazon FBA and warehouses worldwide run on this exact pattern.

Best practices

• Lock stock rows during reservation.
• Track movements — never overwrite qty silently.
• Reconcile movements vs stock daily.

Hands-on exercise

Interview preparation — practice these questions:

• Q1. How to prevent oversell?
• Q2. Movements vs raw qty.
• Q3. Reservation TTL.
• Q4. Multi-warehouse strategy.
• Q5. Reconciliation cadence.