Loading into database usually means transforming the data such that the data is stored as database's internal format. For example, using "LOAD DATA ..." in MySQL or "COPY ... FROM ..." in PostgreSQL.

Here, you aren't storing the data in the database. You don't have to take any additional action to sync the file and db when you add rows to the file, so it's not loaded into the database.

Another benefit of this approach is that it allows you to save storage space by eliminating the need to create a copy of the JSON data in the DB's own internal format.

> You have to map each file to a database table and then execute SQL against that database.

The create statement is just a declaration, and doesn't load data into a postgres table. Instead, it just tells postgres how to access the file. So if I then do a query that is limited to the first few rows, it will only ever need to read the first few "rows" of the file.