3 ms·

Big MySQL deployments typically use pauseless online schema changes tooling like gh-ost: https://planetscale.com/docs/learn/online-schema-change-tools-comparis

• mh- 3y ago
  This is what we do. So "how long" is a difficult thing to put a number on, since you're intentionally throttling it to avoid impacting the database's performance (or building up slave lag).