Re : Empty db.changelog.yml

It sounds like you are on the right track. If you have an existing database and want to start using Liquibase to manage changes, then using the generateChangeLog command to create the initial changelog file is correct, and then the changeLogSync command will mark the database as being managed by Liquibase and in-sync with the changelog you just generated. You can then create new databases with the correct structure using the update command. To make future changes, you add to the changelog file and then run the update command to deploy those changes to the different databases you are managing.