ArcSDE is software that enables ArcGIS applications to store, manage and retrieve data in a RDBMS. The “Arc” comes from the ubiquitous naming convention used by Esri for their products. The SDE part stands for Spatial Database Engine.
ArcSDE is sometimes described as middleware, a layer of software that sits between Esri’s ArcGIS products and RDBMS software and manages data exchanges between them. It makes it possible for GIS data users to utilize their data without need for special knowledge of the underlying RDBMS.
As of ArcGIS 10, ArcSDE supports the commercial RDBMS’s Oracle, SQL Server, DB2, and Informix, and the free and open-source PostgreSQL.
In the last lesson you worked with file geodatabases, a format that Esri recommends for small, single-user projects. Esri often refers to geodatabases stored in an RDBMS and accessed using ArcSDE as multiuser geodatabases because they are better able to support access by more than one user. The advantages of a multiuser geodatabase include:
- Better data security through the granting of different levels of access to datasets to different users
- Backup and recovery capabilities
- Versioning which provides the mechanism for multiple users to access and edit data simultaneously
- Archiving which makes it possible to efficiently track changes made to datasets over time
Esri enables users in the Amazon cloud to pair ArcGIS Server with either Postgres running on the Ubuntu operating system or SQL Server running on Windows. While there would be some benefit to seeing how Postgres operates as an Esri enterprise geodatabase, we're going to proceed with SQL Server on Windows. Most students aren't familiar with Ubuntu and SQL Server is more commonly used in the industry as a geodatabase DBMS. That said, the concepts involved in administering an enterprise geodatabase are similar regardless of the RDBMS used, so what you learn here will be transferrable to other RDBMS’s.
One of the first things you might want to do after launching an enterprise geodatabase is set up login roles and privileges for those roles. That will be the focus of the next section of the lesson.