INF: How DATALENGTH Determines the Length of Text Fields

 Last reviewed: April 25, 1997
Article ID: Q75277

The information in this article applies to: 

  - Microsoft SQL Server version 4.2 for OS/2
  - Microsoft SQL Server version 4.2

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 de-reference 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 query words: de-reference Windows NT dblib
Keywords : kbprg SSrvDB_Lib SSrvServer SSrvWinNT
Version : 4.2 | 4.2
Platform : OS/2 WINDOWS

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Last reviewed: April 25, 1997
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