Online migration: 5 real scaling case studies
5 of the 73 engineering write-ups in our database are tagged with the technique "online migration". They come from 5 companies (Figma, GitHub, Notion, Shopify and Stripe) and were published between 2017 and 2024. Stack that shows up most often in these stories: AWS RDS (2), MySQL (2) and PostgreSQL (2). Often combined with horizontal sharding (2). 1 of the 5 state concrete scale numbers, for example "terabyte scale" (Shopify). Each card below links to our short summary and the original post.
How Figma's Databases Team Lived to Tell the Scale
Figma's nine-month effort to horizontally shard its Postgres stack using a custom query proxy and logical sharding before physical splits.
Herding elephants: Lessons learned from sharding Postgres at Notion
Notion split its Postgres monolith into a fleet of logical shards keyed by workspace, using double-writes and backfills to migrate.
Partitioning GitHub's relational databases to handle scale
GitHub defined schema domains and linted cross-domain queries so it could move table groups onto separate MySQL clusters.
Shard Balancing: Moving Shops Confidently with Zero-Downtime at Terabyte-scale
Shopify rebalances MySQL shards by moving individual shops online with its Ghostferry tool.
Online migrations at scale
Stripe's four-step dual-write playbook for migrating data models without downtime.