// ROUTE_TRANSITION_SYS :: BLOG/DATABASE MIGRATION STRATEGIES ZERO DOWNTIME/
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// KROMA CODE BLOG :: BACKEND ARCHITECTURE
Zero-Downtime Database Migrations: Blue-Green Deployments & Expand-Contract Patterns
Shishir Singh• 12 min read•July 15, 2026
💡 ARTICLE EXECUTIVE SUMMARY: "Renaming a database column during active traffic can crash production APIs. Learn how the Expand-Contract migration pattern guarantees 100% uptime during schema changes."
1. The Expand-Contract Pattern
- Expand: Add new database column while keeping old column intact.
- Write to Both: Application code writes to both old and new columns simultaneously.
- Backfill: Migrate historical data in background batches.
- Contract: Deprecate and drop old column safely once all microservices are updated.
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Backend APIs & Database Architecture // FEATURED CASE STUDY
SGMS World Enterprise System Written by Shishir Singh (Founding Engineer at Kroma Code, Lucknow)
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