Content Hierarchies

Data in an ODABA databases can be collected on different levels.

• Database - A database collects data related to a certain problem or process to be managed (e.g. the resource database containing schema definitions for the problem/process or the data database containing problem/process data, e.g. tax data for a tax consultant).
• Object space - A database may consist of a hierarchy of object spaces, where each object space may cover a separate area of the problem/process (e.g. an object space for each customer of the tax consultant). Object spaces may also get subordinated object spaces.
• Extent - Each object space collects data (object instances) in any number of extents. Each extent is collecting data of the same or different complex data types.
• Instance - An instance is a collection of elementary of complex data type elements according to a given type definition.