Is that true for all database systems? I would think those using MVCC (
https://en.wikipedia.org/wiki/Multiversion_concurrency_contr...) would work fine with COW because they do not generally overwrite data.
On the other hand, the dumber your file system, the meore r database has over what happens on disk. Thats why databases may allow storing data on disk without using any file system in-between.
