Does anyone know why? This still seems to have quite a bit of potential to me.

Besides that: Is my intuition correct that they barely innovated in user-facing features after the early 2000s? Yeah, they broke everyone's workflows once or twice, but nothing about the way things work seems to really have changed, especially not in ways seen before elsewhere.

A file system as a database is one of those things that makes a good pitch but falls down pretty hard once you try implementing it. It falls apart faster if you've got to touch the Internet.

The first and biggest problem is that different types of files have metadata they consider to be important. Author and editor information useful for collaborative editing in a Word document is immaterial to a static raster image saved with a lossy codec. So your database ends up with dozens to hundreds of schemas to store metadata. You still need to serialized and deserialize metadata on files going out or coming in. If some unrelated application (not the authoring application) went and edited the database, which metadata for that file is canonical? The world may never know.

If you're building some metadata management database that's also storing binary blobs on addressed blocks on a disk, you might as well use a traditional file system and have a read-only database on top.

That way the file system stores bytes. An application unrelated to authoring can safely shuffle those bytes over the Internet. It's up to an authoring/editing application to store appropriate metadata.

The files themselves always have the canonical metadata and the read-only database for finding/organizing the files can just update when it's notified of a change in the file.

The database can focus on database things and the file system can make sure bytes go where they need to be. This also gives the flexibility to swap out either the file system or database at any time. This is the way Windows and macOS went and how many Linux DEs work.

They were innovating behind-the-scenes, but the stuff just never made it out. I was doing some forward-looking stuff on contract for them. I thought Windows Phone was innovative, myself, and really easy to develop for, but for whatever reason it never gained the traction of its competitors.

As far as I can tell, the advanced features of Longhorn like WinFS just kept on running over schedule and eventually they had to cut down the scope and release Vista.

That was WinFS in Longhorn, that became Vista. The filesystem as database thing wasn't in the 9x days AFAIK.

Still think it would have been a great idea. Of course it was being planned for Linux too as ReiserFS but then he went off killing his wife and that was the end of that.

Not sure why MS ever dropped the idea of WinFS. It has merit IMO.

Apple tried it as well with the iOS apps being able to dump their files in a flat structure only and organize and find them using labels and search.

It doesn’t work if you have more than a few documents and it isn’t what users want. Users want to be able to organise their documents in folders.

That was a bit different though. It didn't really have labels in a consistent way.

I agree folders are still great to have but I don't think the idea of a database-driven filesystem precludes that. It will just add more organisation options, not take any away.

If you don’t take away folders then the ‘database filesystem’ is not the main way of accessing files. And then it is nothing more than an index like those used by Spotlight or Cortana.

If you’re going to make a drastic move like switching the filesystem paradigm you need some really convincing arguments to sell it. More than ‘some organisation options’.

That was much later. OP is referring to the Cairo project and its Object File System, which was canceled.

Oh ok I didn't realize there was another cancelled project there.

Thanks I'll read up on it.