There is one important exception to the search order for properties described above: When you set the derby.database.propertiesOnly property to true, database-wide properties cannot be overridden by system-wide properties.
This property ensures that a database's environment cannot be modified by the environment in which it is booted. Any application running in an embedded environment can set this property to true for security reasons.
See the "Derby properties" section of the Derby Reference Manual for details on the derby.database.propertiesOnly property.