Database: Consistency Across Services

An order spans multiple services — payments, inventory, notifications. Explain how you keep them consistent without a distributed transaction.

Technical Reference & Key Concepts

The Challenge: Multi-Service Consistency

Order placement calls the Payments service, deducts inventory, and triggers notifications. Each service owns its own database. A network failure mid-flow leaves inconsistent state.

Core questions to address:

  1. Why can't you use a classic distributed transaction across services?
  2. What pattern keeps the services consistent, and what is the failure handling?
  3. What is the eventual-consistency window, and how do users experience it?