ZeroDowntimeMigration
Schema/data changes that don't require taking the system offline — expand/contract pattern, dual writes.
Why we need this / what value this brings
Users don't stop using the app just because a migration is running — downtime during a migration is a self-inflicted outage.
When to use this
Any schema change on a table that's actively read/written by a live system with real users.
How to use or implement this
Use the expand/contract pattern: add the new column/table, dual-write during transition, backfill, then remove the old path once fully migrated.
Research questions
- Does the current migration process require downtime, or has that never actually been tested under load?
Empty folder — drop notes, links, and findings here as you research.