About working with geodatabases and the geoprocessor
Geodatabases are relational databases that contain geographic information. Geodatabases contain feature classes and tables. Feature classes can be organized into a feature dataset and can exist independently in the geodatabase.
Feature classes store geographic features represented as points, lines, or polygons and their attributes; they can also store annotation and dimensions. All feature classes in a feature dataset share the same coordinate system. Tables can contain additional attributes for a feature class or geographic information, such as addresses or x,y,z coordinates.
The geodatabase model defines a generic model for geographic information. This generic model can be used to define and work with a wide variety of different user—or application—specific models. By defining and implementing a wide variety of behavior on a generic geographic model, a robust platform is provided for the definition of a variety of user data models.
The geodatabase supports a model of topologically integrated feature classes similar to the coverage model. However, it extends the coverage model with support for complex networks, topologies, relationships among feature classes, and other object oriented features. The ESRI ArcGIS Desktop applications (ArcMap, ArcCatalog, and ArcGlobe) work with geodatabases as well as coverages and shapefiles.
Successfully implementing a multiuser geographic information system (GIS) with ArcInfo and ArcSDE, starts with a good data model design and database tuning. How the data is stored in the database, the applications that access it, and the client/server hardware configurations are all key factors to a successful multiuser GIS system.
A critical part of a well performing geodatabase is the tuning of the database management system (DBMS) in which it is stored. This tuning is not required for personal geodatabases; however, it is critical for ArcSDE geodatabases. For more information on tuning your database for ArcSDE and the geodatabase, see the Configuration and Tuning Guide for DBMS.
Designing a geodatabase is a critical process that requires planning and revision until you reach a design that meets your requirements. Once you have a design, you can create the geodatabase and its schema using geoprocessing tools. There are tools for creating, modifying, and analyzing your geodatabase schema, such as Create Feature Class, Compress, and Add Subtype.
Personal geodatabases are designed for single use, utilizing Microsoft Access as the database. Multiuser geodatabases use relational database management system (RDBMS) packages, such as Oracle, SQL Server, or IBM DB2. Generic geoprocessing programs should be written to work with either type of geodatabase using the various validation and qualification geoprocessor methods.