VersionPress is a free and open source version control plugin for WordPress built on Git.
We increase major version numbers quite rapidly, e.g., VersionPress is at 3.0 at the time of writing this, but that does not mean it is production-ready.
If these guys have solved the WP devops problem, they will be millionaires and candidates for canonization.
MODX has had something similar for a while with Gitify[1] for the site structure and VersionX[2] for content, but I haven't had much of a chance to use them.
[1] https://github.com/modmore/Gitify [2] https://modx.com/extras/package/versionx
If it is a huge site split the tables into separate files but 1 file is pretty good for most medium sized clients.
Git merging db's can be gnarly if changed significantly, (rollbacks are trivial).
This looks very useful and GPL just like Wordpress - excellent!