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Vector
Data Formats - Geodatabase
Concepts
data formats
geodatabase
feature class
feature dataset
relationship class
topology class
domain
Data format
All vector data are a series of coordinates (which may link together)
related to a set of attributes. However, several formats are used
to store such data. At the most fundamental level, each stores
the location and the attributes, the differences are the way these data
are stored and the added functionality of each format. This is
analogous to a letter which is written in Microsoft Word and then saved
as a WordPerfect file. Both letters have the same exact content,
but the way they are stored is entirely different.
Geodatabase
A geodatabase is a collection of GIS data which is stored in a
relational database. There are two types, personal (stored using
Microsoft Access), and enterprise
(stored in a multi-user database such
as Oracle using Spatial Database
Engine - SDE). A
geodatabase is the newest data format and provides
the powerful functionality of a database with GIS data.
Geodatabases and their contents are indicated by gray icons.
 Enterprise geodatabase
 Personal
geodatabase
Feature class
A feature class in a geodatabase is what
most people would call a data layer. Technically, a collection of
features stored as a single table in a geodatabase is a feature
class. When that feature class is added to a map, it becomes a
data layer.
 Polygon
feature class
 Line
feature class
 Point
feature class
Feature dataset
A geodatabase can store feature classes in a container known as a
feature dataset. Feature classes which share a common spatial
extent and projection, and perhaps topology, can be included in a
feature dataset.
 A feature dataset and its
contents
Relationship class
A geodatabase can store attribute relationships between feature classes
and tables in a relationship class. The relationship class allows
you to query a table or feature class in ArcMap and then see any
related records. For example, you may have a feature class with
sampling locations, and another table with results from samples for
those locations. The relationship class will allow you to
automatically connect these data together in ArcMap. Relationship
classes can also link two feature classes, such as a public well and
its buffer. With a relationship class in place, moving the well
would also move the buffer.
 Relationship class
Topology class
A topology class is similar to a relationship class, except that it
links feature classes by spatial relationship. With a topology
class, you can make the town boundaries and the county boundaries
linked so that they are always coincident.
 Topology class
Domain
A domain is a range or set of values which are valid for a field.
The geodatabase allows you to create one or more domains, and then
assign the domains to fields in feature classes or tables. The
domain will limit the choices a user can make when populating a field,
ensuring consistency among records.
 A
geodatabase domain provides a list of valid values to choose from and
ensures consistency in data.
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