cloud-native-schema-migrations/cloud-native-schema-migrations.github.io

A manifesto on headache-free database schema migrations, working well for cloud-native environments and continuous deployment.

cloud-native-schema-migrations.github.io's Issues

"Always do a full database dump" shouldn't be a principle, make this a suggestion

It might not be possible to do full database dumps.

Add "related work" / links

Two initial articles to include (and comment on)

• https://spring.io/blog/2016/05/31/zero-downtime-deployment-with-a-database
• https://martinfowler.com/articles/evodb.html

Best practice: cleanup / clearly mark compatibility code for later removal

To implement principle 3, code that deals with two versions of a schema should be clearly marked so that it can be cleaned up.

Mention schemahero

https://github.com/schemahero/schemahero looks useful and could be mentioned

Add "zero-downtime" / deployment at all times as motivation

In the introduction don't only mention "cloud-native", but also that the goal is to have zero-downtime, and being able to deploy outside of maintenance windows.

"Checking the schema version" clarification

The "Checking the schema version" is unclear, especially making it clear that it isn't about backwards-incompatible that would require old applications to be stopped (and which is something that shouldn't happen). This is about deploying an application version that needs a schema change, and making sure that the schema change was applied, before starting the application.

Risks of schema-aware code

Implementing schema detection and different code paths in the application has the risk of using untested code.

Rephrase principle 3: "Ensure your application always works with the current and previous schema"

"If needed, adapt first the current application": a) I'd rephrase this to "Ensure your application always works with the current and previous schema". It's such a fundamental concept that I think it deserves to be lifted into a principle. I'd quickly sum up what this means and then condense the rest of the current paragraph into the end of the same section. b) I'd add a fourth step "4. Clean up"

(from Patric)