The following figure shows how the database system searches for the data to be deleted in the B* tree for a DELETE statement.
The address table is defined by the column with the city primary key. The corresponding DELETE statement is used to delete an entry with the Apach value for the city primary key field.
When an entry is deleted from the table, gaps occur in the data area and in the position list of the leaf page in the B* tree. The database system closes these gaps and updates the position list to save storage space.