Rolling back data
On This Lesson 4 topics
This lesson is planned. The outline below lists the topics it will cover. The full lesson has not been published yet.
In this lesson
make data changes reversible, not just code.
Planned topics
- Code rolls back in minutes; schema and data changes may not.
- Expand and contract: add new columns or tables first (expand), migrate, switch reads, and only later remove the old (contract).
- New code must tolerate the old schema and old code the new, so either version can run during rollout.
- When a change is truly irreversible, say so in the review, take a backup or snapshot, and require an explicit go decision.
Draft outline details
Demonstration
Timeline: release N adds a nullable status_v2 column and dual-writes; N+1 reads from it; N+2 drops the old column weeks later. Rollback at any step before N+2 is a deploy, not a restore.
Check your understanding
Why drop the old column in a later release?
Show answer
So rollback to earlier code stays possible while the new path is proven.
Practice
Apply this lesson with the module's lab, exercises and quiz.
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