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Saturday, June 4, 2011

Geographic Database: ESRI File Formats

ESRI gave us two types of file GeoDatabases: File GeoDatabase and Personal GeoDatabase.

So far at all the companies I worked at we used them for upgrading the real database (SQL Server) or as a backup for the Geographic data. Until today Personal GeoDatabase was the best choice for that purpose (we even backed up the file on the TFS).

I have decided to compare the two types:

  File GeoDatabase Personal GeoDatabase
ESRI Description

“A collection of various types of GIS datasets held in a file system folder.(This is the recommended native data format for ArcGIS stored and managed in a file system folder.)”

“Original data format for ArcGIS geodatabases stored and managed in Microsoft Access data files.(This is limited in size and tied to the Windows operating system.)”

Storage Format “Each dataset is a separate file on disk. A file geodatabase is a file folder that holds its dataset files.” “All the contents in each personal geodatabase are held in a single Microsoft Access file (.mdb).”
Size Limits One TB for each dataset. Each file geodatabase can hold many datasets. The 1 TB limit can be raised to 256 TB for extremely large image datasets. Each feature class can scale up to hundreds of millions of vector features per dataset.”

Two GB per Access database. The effective limit before performance degrades is typically between 250 and 500 MB per Access database file.”

Structure a file + a folder full of files one file in access format
adding/removing a feature the files in the folder change (added or deleted) change in the access data
editing the geographic data change in the files change in the access data
Performance better then personal but worse from SDE not good but better than shape
Storage in TFS (or any other source control system) difficult, for each change you should delete the folder and add it again to the TFS (the files in the folder may be deleted or created when changes occur) easy, simply check out the mdb file (be sure not to check in the lock file)
Getting IWorkspace for the GeoDatabase fileGDBWorkspaceFactory.Create(path, "Sample.gdb", null, 0); accessWorkspaceFactory.Create(path, "Sample.mdb", null, 0);

Quotes come from the ESRI site. ESRI compared some more things like number of users, versioning, platform and security but I consider it an overkill for a file GeoDatabase.

Today I am working on a bigger project (something a bit worldwide with a lot of data) and 2GB is just not enough. The good thing is that we probably won’t use the TFS to backup the data but actual IT systems.


ESRI: Types of geodatabases


Keywords: file, GeoDatabase, database, access, mdb, source control, IWorkspace, ESRI, Sde