Sorry, but you obviously don't understand what an index is or let alone how relational databases work. Go read a book about databases, it's too much to go over in a forum topic.
How does your database handle ACID, transactions, locking, integrity constraints. How about "simple" things like table joins or aggregate functions? Or how about user authorization on database/table/column level?
There is more to a DBMS than raw speed on simple selection queries, and that is of course the reason why the world uses real databases like MySQL, Oracle, MS SQL, PostreSQL, etc.