databases solves coordination problems that filesystems couldnt. concurrent writes, atomic transactions, and structured querying across millions of records.

But, filesystem-databases idea is still exists. SQLite is essentially this. and I wrote an adapter for this. from experience, It look like capable of doing everything that other adapters do. but really slowly :D

For example; datrix.update('comment',/where/{ author(another file): { group(another file): { tag: 'abc'} } },/data*/ { name: 'new name', anotherRelation(another file): { connect:[123] } })

to find correct entry, this query has to check 3 file. that It replace all the results name with 'new name' and also connects another file's entry for them. what happens if another user wants to write authors same time. or names updated but while connecting another relation exception happened. I have to get back all updates. how I solved this. I lock filesystem while this query (all other requests blocked) I updated all data in memory and if anything happens on the way I revert. this is how slow this solution. what should I do to fix this. I must create another application. It has to manage all request. without blocking. and this is also we called database engine.