Earlier quoted context omitted.
> Oh, let's not forget the fact that Vista was supposed to be Longhorn, the OS of the future with a database file system This sounded interesting when I first heard about it, long before Vista came out. Now when I see it I wonder what they were trying to do. A file system is a database, with a well understood user API. So what were they going to add? Tagging? Application level views of the system? None of t hat seems…
A file system is a database, with a well understood user API. Yes, a terrible API which works poorly for most home use cases. You probably have music on your computer. In your hierarchical filesystem, do you organize it by Genre/Artist/Album or Artist/Album? Do music videos live in the same Artist directory or in a separate "video" folder? Chances are you don't know/care because you're using an app like iTunes that b…
Data has no feelings.
In the case of file system, it makes perfect sense to be stored in a single static hierarchy because that perfectly reflects the concept of a paper file in a filing cabinet, in a little binder.
Even a relational database system that lets you query tables for data based on set ordering has a single method of storing the data on disk - that's a clustered index. You can't get away from having that, despite being able to support additional nonclustered indexes. In that case, the table and its rows really is organised in a static hierarchy too.
As it stands, NTFS has plenty of features that lets you attach a secondary data stream to a file anyway, and all manner of metadata. The Windows Internals book on NTFS is very informative on this.
These features don't exist on APFS though, as it's not as good despite being brand new, it seems!