Data Storage

The geodatabase supports all the different elements of GIS data that can be used by ArcGIS. By storing data within a geodatabase, you can take advantage of its data management capabilities to leverage spatial information. ArcGIS has a comprehensive suite of data conversion tools to easily migrate existing data into the geodatabase.

The geodatabase is a more robust and extendable data model compared to shapefiles and coverages. It is designed to make full use of the capabilities of ArcGIS Desktop and ArcGIS Server.

Read an ArcNews article to find out more about data storage in the geodatabase.

GIS Data in a Geodatabase

The geodatabase supports all the different elements of GIS data used by ArcGIS. The structural elements of a geodatabase, listed below, are some of the elements used to develop a rich GIS, such as

• Attribute data
• Geographic features
• Satellite and aerial images (raster data)
• CAD data
• Surface modeling or 3D data
• Utility and transportation systems
• GPS coordinates
• Survey measurements

Geodatabases can represent these types of data as the following data objects:

Annotation

A specialized feature class that stores text or graphics that provide information about features or general areas of a map. An annotation feature class may be linked to another feature class so that edits to the features are reflected in the corresponding annotation (i.e., feature-linked annotation).

Cadastral Fabric

A seamless parcel boundary network, which is created and maintained using data from survey records. Parcels are represented by parcel line features, parcel point features, and parcel polygon features, referred to in aggregate as parcel features. Parcel topology in the cadastral fabric is stored explicitly through shared or common parcel point features.

Dimension

A special type of geodatabase annotation that shows specific lengths or distances on a map. A dimension feature may indicate the length of a side of a building or land parcel, or it may indicate the distance between two features such as a fire hydrant and the corner of a building.

Feature Class

A collection of geographic features with the same geometry type (i.e., point, line, or polygon), the same attributes, and the same spatial reference. Feature classes allow homogeneous features to be grouped into a single unit for data storage purposes, for example, highways, primary roads, and secondary roads can be grouped into a line feature class named "roads." Feature classes can also store annotation and dimensions.

Feature Dataset

A collection of feature classes stored together that share the same spatial reference. Feature classes in a feature dataset share a coordinate system, and their features fall within a common geographic area. Feature datasets are used to help model spatial relationships between feature classes.

Geometric Network

Edge and junction features that represent a directed-flow system network, such as a utility or hydrologic system, in which the connectivity of features is based on their geometric coincidence. A geometric network does not contain information about the connectivity of features; this information is stored within a logical network. Geometric networks are typically used to model directed-flow systems.

Network Dataset

A collection of topologically connected network elements (e.g., edges, junctions, and turns) that are derived from network sources, typically used to represent an undirected-flow system network such as a road or subway system. Each network element is associated with a collection of network attributes. Network datasets are typically used to model undirected-flow systems.

Raster Catalog

A collection of raster datasets defined in a table of any format, in which the records define the individual raster datasets that are included in the catalog. Raster catalogs can be used to display adjacent or overlapping raster datasets without having to mosaic them together in one large file.

Raster Dataset

Any valid raster format organized into one or more bands. Each band consists of an array of pixels (cells), and each pixel has a value (e.g., a Landsat satellite image). Raster datasets can be stored in many formats, including TIFF, ERDAS Imagine, ESRI Grid, and MrSID.

Relationship Class

A class similar to relationships that exist within an RDBMS. Relationship classes manage the associations between objects in one class (e.g., table or feature class) and objects in another. Objects at either end of the relationship can be features with geometry or records in a table.

Schematic Dataset

A dataset used for graphically representing network connectivity. It also represents sets of relationships.

Survey Dataset

An integrated collection of specialized survey feature classes. It also contains associated survey measurements.

Table

A set of data elements arranged in rows and columns. Each row represents a single record. Each column represents a field of the record. Rows and columns intersect to form cells, which contain a specific value for one field in a record. Tables typically store stand-alone attribute information or information associated with a spatial location such as addresses.

Terrain

A triangulated irregular network (TIN)-based dataset that uses feature classes as data sources to model multiple resolution surfaces using z-values.

Toolbox

A collection of dataflow and workflow processes. These are used for performing data management, analysis, and modeling.

Topology

The arrangement that constrains how point, line, and polygon features share geometry within a geodatabase. For example, street centerlines and census blocks share geometry, and adjacent soil polygons share geometry. Topology defines and enforces data integrity rules, topological relationship queries and navigation, and sophisticated editing tools. It also allows feature construction from unstructured geometry.