Table access using a B* tree is illustrated using the example of an UPDATE statement.
· If an UPDATE is performed and the primary key remains unchanged, only the contents of the table row are changed.
· If the data length changes, the positions of subsequent entries and their addresses in the position list of the leaf page in the B* tree are changed.
· If the key field changes, the UPDATE is executed as a DELETE (see Table Access (DELETE) Using a B* Tree) with a subsequent INSERT (see Table Access (INSERT) Using a B* Tree).