PHYSICAL DATABASE DESIGN - Fundamentals of Database Management Systems - page 212

253 477 641

To
Cyl
1

To
Cyl
2

To
Cyl
3

To
Cyl
4

To
Cyl
5

To
Cyl
6

To
Cyl
7

To
Cyl
8

To
Cyl
9

To
Cyl
10

140 192 253 307 368 416 477 529 578 641

Records
with
Salesperson
Numbers
081-140

Records
with
Salesperson
Numbers
145-192

Records
with
Salesperson
Numbers
197-253

Records
with
Salesperson
Numbers
260-307

Records
with
Salesperson
Numbers
310-368

Cylinder 1 Cylinder 2 Cylinder 3 Cylinder 4 Cylinder 5

Records
with
Salesperson
Numbers
371-416

Records
with
Salesperson
Numbers
422-477

Records
with
Salesperson
Numbers
479-529

Records
with
Salesperson
Numbers
533-578

Records
with
Salesperson
Numbers
582-641

Cylinder 6 Cylinder 7 Cylinder 8 Cylinder 9 Cylinder 10

F I G U R E 8.14
Salesperson file with a B + -tree index

Alternatively, you can think of it as a family tree, which normally has this same
kind of top-to-bottom orientation.

Roots

Ground

Node

F I G U R E 8.15
A real tree, upside down, with the roots
clumped together into a single point

Leaf
(“Terminal Node”)