If you use alter database to add space on a database device that is new to the database, the system and default segments are extended to include the new space. Thus, the scope of the system and default segments is extended each time you add a new device to the database.
If you use alter database to assign additional space on an existing database device, all the segments mapped to the existing device are extended to include the new device fragment. For example, assume that you initialized a 4MB device named newdev, allocated 2MB of the device to mydata, and assigned the 2MB to the testseg segment:
alter database mydata on newdev = "2M"
sp_addsegment testseg, mydata, newdev
If you alter mydata later to use the remaining space on newdev, the remaining space fragment is automatically mapped to the testseg segment:
alter database mydata on newdev = "2M"
See “A segment tutorial” for more examples about how Adaptive Server assigns new device fragments to segments.
