SDB_PhysicalMainBase - Physical mainbase definition

A physical main base definition is required, when a main base is supposed to consist of more than one data area or when the root base contains several mainbases. Mainbases are using a consecutive number starting with 0. Mainbase 0 is the default mainbase defined for the rootbase.

When no main base is defined in a database schema, main base 0 with a dynamic data area 0 will be created when creating a rootbase for a new database.

Mainbase numbers are stored in 16 high order bytes of the database entry number (LOID). High and low number define the range of valid main base numbers within an LOID. Usually, the values for low and high are identical with the main base number, since the lower 48 bit for numbering database entries within a mainbase are sufficient for most main bases.

A physical schema can be defined using main base definitions in the main base extent ( SDB_MainBase ). Additional physical schemata might be defined by means of root base definitions ( SDB_RootBase ).