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System Design•July 6, 2026•8 min read
Zero-Downtime Database Migrations: The Expand-Contract Pattern in Production
How to rename database columns and alter schema types on 500-million row Postgres tables without holding table locks.
Kalash JindalAuthor
Postgres Schema Architecture
Phase 1: Expand, Phase 2: Dual Write & Backfill, Phase 3: Contract.