Zero-Downtime Database Migrations

Technique for modifying relational database schemas (e.g. renaming columns, adding indexes) without locking tables or interrupting active user traffic.

STAFF ENGINEER TAKEAWAY: The Expand and Contract pattern: Add new column -> Dual-write to both -> Backfill historical rows -> Read from new column -> Drop old column.

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More Topics in 10. Deployment & DevOps

🔄CI/CD Continuous Integration & Delivery

Automates testing, linting, container building, and deployment of code updates, accelerating release velocity from months to minutes.

🔵🟢Blue-Green Deployment Strategy

Maintains two identical production environments (Blue and Green). One serves live traffic while the other is updated. Traffic is cut over instantly at the router.

🐤Canary Deployment Strategy

Rolls out new software to a tiny subset of users (e.g. 2%), monitors error rates and latency, and incrementally shifts remaining traffic if health checks pass.

🔄Rolling Deployment Strategy

Incrementally updates instances of an application by replacing old pods/servers with new ones one by one or in small batches.