The Topology Data Model feature of Oracle Spatial lets you work with data about nodes, edges, and faces in a topology.

For example, United States Census geographic data is provided in terms of nodes, chains, and polygons, and this data can be represented using the Spatial Topology Data Model feature. You can store information about topological elements and geometry layers in Oracle Spatial tables and metadata views. You can then perform certain spatial operations referencing the topological elements, for example, finding which chains (such as streets) have any spatial interaction with a specific polygon entity (such as a park).

This chapter describes the spatial data structures and data types that support the Topology Data Model feature, and what you need to do to populate and manipulate the structures. You can use this information to write a program to convert your topological data into formats usable with Spatial.

• Main Steps in Using Topology Data
  This topic summarizes the main steps for working with topology data.
• Topology Data Model Concepts
  Topology is a branch of mathematics concerned with objects in space. Topological relationships include such relationships as contains, inside, covers, covered by, touch, and overlap with boundaries intersecting.
• Topology Geometries and Layers
  A topology geometry (also referred to as a feature) is a spatial representation of a real world object. For example, Main Street and Walden State Park might be the names of topology geometries.
• Topology Geometry Layer Hierarchy
  In some topologies, the topology geometry layers (feature layers) have one or more parent-child relationships in a topology hierarchy. That is, the layer at the topmost level consists of features in its child layer at the next level down in the hierarchy; the child layer might consist of features in its child layer at the next layer farther down; and so on.
• Topology Data Model Tables
  To use the Oracle Spatial topology capabilities, you must first insert data into special edge, node, and face tables, which are created by Spatial when you create a topology.
• Topology Data Types
  The main data type associated with the Topology Data Model is SDO_TOPO_GEOMETRY, which describes a topology geometry.
• Topology Metadata Views
  There are two sets of topology metadata views for each schema (user): xxx_SDO_TOPO_INFO and xxx_SDO_TOPO_METADATA, where xxx can be USER or ALL. These views are read-only to users; they are created and maintained by Oracle Spatial.
• Topology Application Programming Interface
  The Topology Data Model application programming interface (API) consists of the following.
• Exporting and Importing Topology Data
  You can export a topology from one database and import it into a new topology with the same name, structures, and data in another database, as long as the target database does not already contain a topology with the same name as the exported topology.
• Cross-Schema Topology Usage and Editing
  This topic contains requirements and guidelines for using and editing topologies when multiple database users (schemas) are involved.
• Function-Based Indexes Not Supported
  You cannot create a function-based index on a column of type SDO_TOPO_GEOMETRY.
• Topology Examples (PL/SQL)
  This topic presents simplified PL/SQL examples that perform Topology Data Model operations.
• README File for Spatial and Related Features
  A README.txt file supplements the information in the following manuals: