If database-file does not
exist it is created as an sqlite3 database file.
The database schema described in this section is
then created in the database file.
If database-file alread existed:
If it is not an sqlite3 database an error is thrown.
If it is an sqlite3 database, the schema required to make the file suitable for a configuration database file is layered on top of any existing schema. Note that if any or all of the schema already exists no harm is done as tables and indices are created using CREATE xxxx IF NOT EXISTS....