

Object( x, y, otherattributes ) // x and y are the // coordinates of the object 


(The point with the smallest xcoordinate value is the leftmost leaf key)
(The point with the smallest ycoordinate value is the leftmost leaf key)



Green area = 100 × 100 = 10,000 Total area = 1000 × 1000 = 1,000,000 Green area = 0.01 × Total area 


Comment:

There are 1,000,000 points 1 disk block stores 100 points # disk blocks used = 1,000,000 / 100 = 10,000 blocks 
So we would need:
10,000 disk blocks accesses 
So using the Btree index does not help us improve performance !!!
