ArcGIS 10: What is a Geodatabase?

What is a Geodatabase?

John Baldridge, PhD
February 2012

A geodatabase is an alternate way to store GIS information in one large file, which can contain multiple point, polygon, and/or polyline layers. ESRI is pushing the geodatabase idea, because it is a less “messy” way of organizing data than having multiple shapefiles. in multiple folders. While shapefiles are still very popular and commonly available, you may run into geodatabases in your search for useful data. Here are the basics:

• Geodatabases often appear as single files with the “.gdb” extension or “.mdb” extension.
• In a GDB, “shapefiles” are referred to as “feature classes.” Otherwise, they perform the same function when you add them as layers to your map in ArcGIS
• That’s it, at least for beginners!

Example: Go to the TESC GIS web page at http://scicomp.evergreen.edu/cal/gis/index.html

1) Click the link for the Washington State Geospatial Data Archive
2) Click “DATA” at the top of the page and then “Data by Geography”
3) Click “Washington State”
4) Under “Census/Demographic Data”, click “WAGDA 2000 Census Geodatabases”
5) Scroll down to “2010 SF1 Geodatabases”
6) Choose a county and download the file. Unzip it.
7) Note that a folder with the “.gdb” extension appears.
8) “Add Data” in ArcMap and browse to that folder. You can add the feature classes and tables inside.

Example: WA Dept. of Natural Resources http://www.dnr.wa.gov/ResearchScience/Topics/GeosciencesData/Pages/gis_data.aspx

You will find a number of downloadable GDBs on this page.