Show Navigation | Hide Navigation
You are here:
Geodatabases and ArcSDE > An overview of the Geodatabase

Types of geodatabases

Release 9.2
Last modified January 14, 2008
E-mail This Topic Printable Version Give Us Feedback

Print all topics in : "An overview of the Geodatabase"

The geodatabase is a "container" used to hold a collection of datasets. There are three types:

  1. File Geodatabases—Stored as folders in a file system. Each dataset is held as a file that can scale up to 1 TB in size. This option is recommended over personal geodatabases.
  2. Personal Geodatabases—All datasets are stored within a Microsoft Access data file, which is limited in size to 2 GB.
  3. ArcSDE Geodatabases—Stored in a relational database using Oracle, Microsoft SQL Server, IBM DB2, or IBM Informix. These multiuser geodatabases require the use of ArcSDE and can be unlimited in size and numbers of users.
Comparing the three types of Geodatabases
Key Characteristics ArcSDE Geodatabase File Geodatabase Personal Geodatabase
Description A collection of various types of GIS datasets held as tables in a relational database
This is the recommended native data format for ArcGIS stored and managed in a relational database.
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.

Number of Users Multiuser
Many readers and many writers

ArcSDE can be licensed for use at three levels:
  • Personal ArcSDE
  • Workgroup ArcSDE
  • Enterprise ArcSDE
Single user and small workgroups
Some readers and one writer per feature dataset, standalone feature class or table.
Concurrent use of any specific file eventually degrades for large numbers of readers.

Single user and small workgroups with smaller datasets
Some readers and one writer.
Concurrent use eventually degrades for large numbers of readers.
Storage Format
  • Oracle
  • Microsoft SQL Server
  • IBM DB2
  • IBM Informix
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

Up to DBMS limits One TB for each dataset. Each file geodatabase can hold many datasets
Each feature class can scale up to hundreds of millions of vector features per dataset.

Two GB per Access database
Effective limit before performance degrades is typically between 250 and 500 MB per Access database file.
Versioning Support Fully supported across all DBMSs; includes cross-database replication and updates

Not supported Not supported
Platforms Windows, Unix, Linux, and direct connections to DBMSs that can potentially run on any platform on the user's local network

Cross-platform Windows only
Security and Permissions Provided by DBMS

Operating file system security

Windows file system security
Database Administration Tools Full DBMS functions for backup, recovery, replication, SQL support, security, and so on

File system management Windows file system management

Requires the use of ArcSDE

Allows you to optionally store data in a read-only compressed format to reduce storage requirements

Often used as an attribute table manager (via Microsoft Access). Users like the string handling for text attributes.

Learn about creating geodatabases

File geodatabases and personal geodatabases

File and personal geodatabases, which are freely available to all ArcGIS users (i.e., users of ArcView, ArcEditor, and ArcInfo), are designed to support the full information model of the geodatabase. This includes topologies, raster catalogs, network datasets, terrain datasets, address locators, and so on. File and personal geodatabases are designed to be edited by a single user and do not support geodatabase versioning. With a file geodatabase, it is possible to have more than one editor at the same time providing they are editing in different feature datasets, standalone feature classes or tables.

The file geodatabase is a new geodatabase type released in version 9.2. Its goals are to

Personal geodatabases have been used in ArcGIS since their initial release in Version 8.0 and have used the Microsoft Access data file structure (the .mdb file). They support geodatabases that are limited in size to 2 GB or less. However, the effective database size is smaller, somewhere between 250 and 500 MB before the database performance starts to slow down. Personal geodatabases are also only supported on the Microsoft Windows operating system. Users like the table operations they can perform using Microsoft Access on personal geodatabases. Many users really like the text handling capabilities in Microsoft Access for working with attribute values.

ArcGIS will continue to support personal geodatabases for numerous purposes. However, it is also highly recommended to use the file geodatabase. It is ideal for working with file-based datasets for GIS projects, for personal use, and for use in small workgroups. It has strong performance and scales well to hold extremely large data volumes without requiring the use of a DBMS. Plus, it is portable across operating systems.

Typically, users will employ multiple file or personal geodatabases for their data collections and access these simultaneously for their GIS work.

ArcSDE geodatabases

When you need a large multiuser geodatabase that can be edited and used simultaneously by many users, the ArcSDE geodatabase provides a good solution. It adds the ability to manage a shared, multiuser geodatabase as well as a number of critical version-based GIS workflows. The ability to leverage your organization's enterprise relational databases is a key advantage of the ArcSDE geodatabase.

ArcSDE geodatabases work with a variety of DBMS storage models (IBM DB2, Informix, Oracle, and SQL Server). ArcSDE geodatabases are primarily used in a wide range of workgroups, departments, and enterprise settings. They take full advantage of their underlying DBMS architectures to support

Through many large geodatabase implementations, it has been found that DBMSs are efficient at moving in and out of tables the type of large binary objects required for GIS data. In addition, GIS database sizes and the number of supported users can be much larger than with GIS file bases.

For information about the ArcSDE geodatabase architecture and how ArcSDE geodatabases leverage relational database technology, see Architecture of the geodatabase.

There are three levels for accessing and using ArcSDE in ArcGIS

ArcSDE geodatabases readily scale from personal, single-user geodatabases through workgroup geodatabases, and on up to extremely large enterprise geodatabases. ArcSDE geodatabase capabilities are available in the following ESRI software products:

To learn more about ArcGIS Server, see An overview of GIS services.
Summary points

You do not need to monitor and manage the use of your memory and cpu's for SQL Server Express. The SQL Server Express software will automatically limit computer use to 1 GB RAM on a single cpu and to a database size of 4GB.
Personal ArcSDE is included free as a part of ArcEditor and ArcInfo. If you choose to install SQL Server Express, you can administer SQL Server Express databases using ArcCatalog.
When you install the ArcGIS Server for Workgroups, you can install and use SQL Server Express and ArcSDE. After installing SQL Server Express, you can use ArcCatalog to administer SQL Server Express databases on your computer.
These various levels enable users to take full advantage of ArcSDE geodatabases for any number of users, large or small. It allows organizations to have one scalable data architecture that works across their single user systems up into their large enterprise systems.

ArcSDE provides long and short transaction management on the DBMS transaction framework

The ArcSDE geodatabase includes advanced support for managing edits and updates to a multiuser geodatabase. As GIS increasingly adds users and the requirement to manage data from an array of sensor networks, the need for transaction management becomes more critical. In GIS, long transactions are needed along with the more common, short database transactions that are orchestrated on the DBMS's short transaction framework.

Often, GIS users have specialized transactional requirements, one of which is the need for some transactions to span long periods of time (sometimes hours, even days and months, not just seconds or minutes).

Additionally, a single editing session in a GIS can involve changes to multiple rows in multiple tables. Users need to be able to undo and redo changes. Users want to treat each edit session as a single transaction when they commit their changes. Furthermore, the edits must often be performed in a system that is disconnected from the central, shared database.

During these specialized GIS data flow processes, the GIS database must remain continuously available for daily operations, where each user might have a personal view or state of the shared GIS database.

In a multiuser database, the GIS transactions must be orchestrated on the DBMS's short transaction framework. ArcSDE plays a key role during these operations by managing the high-level, complex GIS transactions on the simple DBMS transaction framework.

ArcSDE does this by storing change information as delta records in the database; isolating multiple edit sessions using versions; and supporting complex transactions, automatic archive, and historical queries.

See An overview of editing and maintaining data for more information.

Please visit the Feedback page to comment or give suggestions on ArcGIS Desktop Help.
Copyright © Environmental Systems Research Institute, Inc.