Toaster, why are many databases not hierarchical?

Question

MySQL

What I don't understand is why mysql is so flat. Why not make the database hierarchical like an XML file?

Answer 1

There are a large number of graph databases, the most famous being Neo4j and HypergraphDB.
A hierarchical base is a special case of a graph.
In practice, with their help it is convenient to solve a very narrow range of specific problems.
For ordinary stories, a classic relational database is more convenient.

Answer 2

Because there are hierarchical databases (Microsoft Folder, it seems, is called. Explorer, etc.)
There are schemaless
There are relational
There were many more structures. Some have died out, some have found their niches, some have become popular.

Answer 3

Because in relational you add an idParent column to the table - and it becomes hierarchical

Answer 4

I answer - read what types of databases
AI is also a kind of database at the heart of the type of sematic network
there are also multidimensional databases