2011

About Geospatial Feature Classes, Data Stores, and
Schemas
Overview of Geospatial Data
Geospatial data is organized as follows:
■ Feature: The spatial representation of a real-world entity, such as a specific
road or an individual utility pole, that specifies the geometry and other
properties of the feature.
■ Feature class: A category of features with rules that define the allowable
data types, default values, and constraints for its member features. For
example, you might have feature classes for a set of roads, utility poles,
and so on.
■ Schema: A collection of related feature classes.
■ Data store: A collection of feature data in a single storage location.
SDF data stores allow only one schema per file, but database stores such
as Oracle or SQL Server can have multiple schemas. (SHP files can include
only one geometry type per file, but you can be store and copy multiple
SHP files in a folder. You can use a configuration file to support multiple
schemas when you establish your connection to a SHP file.)
NOTE This functionality affects geospatial feature data only. For information about
managing drawing objects and drawing files, see
Overview of Setting Up Your
Map File
(page 140)
The data hierarchy
Geospatial data is stored in a hierarchical fashion, like a set of tables: each
row within a table is an individual feature, and each column is a
property
(page 2071) of that feature. The entire table (including its name, column names,
data types, default values, and constraints) represents a feature class. The set
of related tables is called a schema, and the entire collection of data resides
in a data store.
For example, you might use a data store such as Oracle, which can encompass
multiple schemas. The database might define the utilities for a town, with
schemas for different types of utilities, such as electrical and water. The
electrical schema would include feature classes for utility poles and boxes,
while the water schema would include feature classes for pipes and hydrants.
About Geospatial Feature Classes, Data Stores, and Schemas | 551