Calculating the Size of a 9,000,000-Row Table
with a Clustered Index

The following example calculates the size, in 2K pages, of the data and clustered index for a table containing:

The five steps previously discussed were used to ascertain the table size.

Calculate the data row size.

4 Overhead

+ 100 Sum of bytes in all fixed-length columns

+ 50 Sum of bytes in all variable-length columns

———--

154 Subtotal

+ 1 (Subtotal / 256) + 1 (Overhead)

+ 3 Number of variable-length columns + 1

+ 2 (Overhead)

———--

160 Data row size

Calculate the number of data pages.

2,016/160 = 12 data rows per page

9,000,000/12 = 750,000 data pages

Calculate the size of clustered index rows.

    5 Overhead

+ 4 Sum of bytes in the fixed-length index keys

———--

    9 Clustered index row size

Calculate the number of clustered index pages.

(2,016/9) — 2 = 222 clustered index rows per page

750,000/222 = 3,378 index pages (level 0)

3,378/222 = 15 index pages (level 1)

15/222 = 1 index page (level 2)

Calculate the total number of pages.