INF: How DATALENGTH Determines the Length of Text Fields

ID Number: Q75277

1.10 1.11 4.20

OS/2

Summary:

The DATALENGTH function does not need to traverse the entire text page

chain to determine how long the text field is, because the length is

stored on the first page in the chain. Therefore, although SQL Server

must dereference the pointer stored in the row on the data page to

determine the location of the text page, then read the text page, the

overhead is small.

Additional reference words: 1.10 1.11 4.20 de-reference