Yes! And by extension the tar utility is not a DBMS even if it checks some of the boxes for one. And thus SQLite files are not RDBMSs. Looks like you and I agree.
> The database can be physically stored in any arbitrary format. One can build an RDBMS that stores all its data in tar or JSON files. No matter how inefficient as long as software exists that manages the database.
Sure! One can come up with all kinds of very terrible software. But what's the distinction between some random software that just allows CRUD operations on a file format and an RDBMS by your definition? Because you've defined something close to 100% of all software as an RDBMS which makes the distinction between software and RDBMSs meaningless.
There has to be something more than just that to be an RDBMS doesn't there?
The database can be physically stored in any arbitrary format. One can build an RDBMS that stores all its data in tar or JSON files. No matter how inefficient as long as software exists that manages the database.
>Are .tar files RDBMSs?
This question doesn't make sense because you are asking if databases can be management systems which is obviously false by definition.
If the 5 steps you have described are implemented in software then that software would be considered an RDBMS and the .tar file clearly would be a database. There is no confusion.
>However, you need to build a server, user access controls, connection pooling, import/export tools, partitioning, clustering, etc. before you start to arrive at an RDBMS that uses this engine.
Those features are not necessary for a piece of software to be called RDBMS but most industry standard RDBMS do indeed support these features and SQLite clearly is an RDBMS that pursues a certain niche that only makes sense in certain situations.