Friday, March 11, 2005

Unextracted versus Extracted Data

Many people ask what the difference is between Extracted and Unextracted data is to GTViewer. This is a good question because to the end user it appears to be the same. There are different uses for each and I will explain these below:

Unextracted Data (.GTM)

  • Unextracted data is what is created when data is converted to the GTViewer format.
  • Unextracted data always contains a .GTM file and all of its dependencies (.gtg, .gtn, .flt, .dfn, etc.) See previous post for more information on the different file types.
  • The .GTM file is the file you open in GTViewer or the file you create a new Session from in GTViewer.
  • Unextracted Data can be used by GTViewer, GTVx, GTWeb Server, GTPack, and GTExtract.
  • Unextracted Data is never modified by the end-user. It can be shared with any number of users simultaneously.
  • A Session File (.gts) is always created to store user information and redlines when a .GTM file is opened in GTViewer.
  • You can update any of the components of the Extracted Data without updating the entire thing.
  • Incremental Updates are supported with Unextracted.

Extracted Data (.GTX)

  • Extracted Data is single file, the .GTX file. The file is self-contained and includes all graphic data, tabular data, queries, display settings, etc.
  • Extracted data is created by GTViewer (Extract Command), GTVx, GTPack, GTExtract, GTExtractX, and GTWeb Server. GTViewer can create an Extract file by placing a rectangular fence or a Polygon in the map view and then extracts only the data in the specified area.
  • Pocket GTViewer only reads Extract Files. GTViewer, GTVx, GTWeb Server, GTPack, and GTExtract can read Extract Files as well.
  • An Extract File contains a session file and can store all of the user session information such as redlines, display settings, etc. When used in this mode, an Extract file is a single user file. However, a Session File (.gts) can be created with an Extract file too (just like it is with a .GTM file) and will allow a .GTX file to be used by multiple users simultaneously.
    The only data not stored in an Extract File are Raster files and externally linked file.
  • Extract Files support Passwords and data expiration.

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