DBExtend :: GetMainBase - Get main base number
The main base number for an extent defines, in which main bases instances of the extent are stored. Main base information is relevant for owning extents.
When defining distributes databases, the main base number allows allocating a specific main base for storing instances created in the context of an owning collection.
The main base number for instances and index entries is set automatically, when allocating a main base to the extent.
Main base numbers should not be defined together with the cluster option, since in this case, the cluster creating instance determines the main base for storing data.
The main base number determines the main base for storing indexes for the collection. Instances owned by the extent are stored in the defined main base, too. Indexes and instances owned by other instances are stored in the same main base as the owning instance, i.e. in the main base of the owning extent. Since the owner hierarchy is unique, the main base for an instance can always be obtained from the schema definition.