How to: Represent closely related file types as a single file type


NSS uses File Type Groups to allow for better summary information to be displayed in its file service usage analyses. Groups are based on file extensions. The solution ships with default groups that can be edited to fit a customer's exact needs.

Work to group files appropriately can be made complicated when the customer is using applications that incorporate information into the output files that they create. Leading to situations where files of the same type have different extensions. This complexity is compounded when applications automatically increment the data they add to the extension; when dates or application version numbers are added for example.

NSS 9.7 SR2 introduces the possibility to use regular expressions in File Type Group definitions to make administration of this scenario more straightforward, and automated.

Procedure Overview

  1. Open the NSS Config page and go to the File Types Management control.

    NSS Config Page 
  2. Select the File Type Group that you wish to add file types to and click Add Type...
  3. Enter your regular expression into the File Type Definition dialog box and click OK.

     NSS Config Page regex
  4. The configuration is now complete. Changes will take effect after the next Data Scan. Historical data will be unchanged.

Note that if a file extension matches a regular expression AND a specific entry in a File Type Group, the entry in the File Type Group supersedes the regular expression. If a file extension is matched in multiple regular expressions, the first in alphabetical order will be used.


The examples below provide further understanding of how this feature can be used. The Microsoft Developer Network offers a number of resources detailing Regular Expressions, including this Regular Expression Reference Guide. If more information or guidance is required, do not hesitate to contact Northern's Technical Support team.

A '^' matches the beginning of the target string, and a '$' matches the end of the target string. To match a complete string, enclose the pattern in these start and end markers. To match the start of a string use '^' only. To match the end of a string use '$' only. To match anywhere in the string, use no markers.

  • regex:^[0-9]+$
    Matches all-numerical extensions, such as:
  • regex:^xml.*
    Matches any file extension beginning with "xml", such as:
  • regex:^log[0-9]{8}$
    Matches any extension with the term "log" followed by eight numbers, such as:
  • regex:^[0-9]{2}[A-Z]{3}[0-9]{2}_[0-9]{2}_[0-9]{2}$
    Matches file extensions with the following pattern of numbers and letters:

How Data is Stored

It may be important to understand exactly how the use of regular expressions to group file types effects data representation in the NSS database.

Individual file types that match the expression will not be added to the FILETYPES table during scanning, but its size, count, etc. is aggregated into one summary row that references the file type pattern.

The FILETYPES table is referenced from e.g. the DATASUM, DATA1 and DATA2 tables. The aging tables, which have a string instead of the FILETYPES.ID as a FileTypeName, will also contain the regex pattern instead of a file extension.

KB Article: 3149

Updated: 12/12/2016

  • Category
    • Usage
  • Affected versions
    • 9.70.20083.1605 [9.7 SR2]
    • 9.70.20161.1606 [9.7 SR3]
    • 9.70.20304.1608 [9.7 SR4]
    • 9.70.20363.1609 [9.7 SR5]
    • 9.70.20574.1611 [9.7 SR6]
    • NSS 9.8

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