What is a database migration?

[stefano.menci]

Thanks for the answer Jay, but I still don’t understand.

@jshaffstall

there’s the version of the database as it actually exists, and the version as represented in the .yaml file

Yes, I understand there are two descriptions of the database, one useful, the database itself, and one in the yaml which all it does is being out of sync and asking me to update it. What is that for?

@jshaffstall

Normally Anvil does a pretty good job of automatically updating the app when you make changes to the database, but sometimes that doesn’t happen.

I don’t know when it fails to update it. I gave up long time ago keeping track with it. All my apps say it is out of sync and they work just fine. So… why do I need to fix it if it ain’t broke?

@jshaffstall

When you’re migrating changes between branches, it’s generally the other way, you want to update the other branch’s database from the app (assuming the app was up-to-date!)

I don’t understand what that means.