Chapter 16. Spatial Extensions

Table of Contents

16.1. Introduction to MySQL Spatial Support
16.2. The OpenGIS Geometry Model
16.2.1. The Geometry Class Hierarchy
16.2.2. Class Geometry
16.2.3. Class Point
16.2.4. Class Curve
16.2.5. Class LineString
16.2.6. Class Surface
16.2.7. Class Polygon
16.2.8. Class GeometryCollection
16.2.9. Class MultiPoint
16.2.10. Class MultiCurve
16.2.11. Class MultiLineString
16.2.12. Class MultiSurface
16.2.13. Class MultiPolygon
16.3. Supported Spatial Data Formats
16.3.1. Well-Known Text (WKT) Format
16.3.2. Well-Known Binary (WKB) Format
16.4. Creating a Spatially Enabled MySQL Database
16.4.1. MySQL Spatial Data Types
16.4.2. Creating Spatial Values
16.4.3. Creating Spatial Columns
16.4.4. Populating Spatial Columns
16.4.5. Fetching Spatial Data
16.5. Analyzing Spatial Information
16.5.1. Geometry Format Conversion Functions
16.5.2. Geometry Functions
16.5.3. Functions That Create New Geometries from Existing Ones
16.5.4. Functions for Testing Spatial Relations Between Geometric Objects
16.5.5. Relations on Geometry Minimal Bounding Rectangles (MBRs)
16.5.6. Functions That Test Spatial Relationships Between Geometries
16.6. Optimizing Spatial Analysis
16.6.1. Creating Spatial Indexes
16.6.2. Using a Spatial Index
16.7. MySQL Conformance and Compatibility

MySQL supports spatial extensions to allow the generation, storage, and analysis of geographic features. Before MySQL 5.0.16, these features are available for MyISAM tables only. As of MySQL 5.0.16, InnoDB, NDB, BDB, and ARCHIVE also support spatial features. (However, the ARCHIVE engine does not support indexing, so spatial columns in ARCHIVE columns cannot be indexed. MySQL Cluster also does not support indexing of spatial columns.)

Although spatial extensions are supported in InnoDB tables, use of spatial indexes may cause a crash. (Bug #15860)

This chapter covers the following topics:

Additional resources

16.1. Introduction to MySQL Spatial Support

MySQL implements spatial extensions following the specification of the Open Geospatial Consortium (OGC). This is an international consortium of more than 250 companies, agencies, and universities participating in the development of publicly available conceptual solutions that can be useful with all kinds of applications that manage spatial data. The OGC maintains a Web site at http://www.opengis.org/.

In 1997, the Open Geospatial Consortium published the OpenGIS® Simple Features Specifications For SQL, a document that proposes several conceptual ways for extending an SQL RDBMS to support spatial data. This specification is available from the OGC Web site at http://www.opengis.org/docs/99-049.pdf. It contains additional information relevant to this chapter.

MySQL implements a subset of the SQL with Geometry Types environment proposed by OGC. This term refers to an SQL environment that has been extended with a set of geometry types. A geometry-valued SQL column is implemented as a column that has a geometry type. The specification describe a set of SQL geometry types, as well as functions on those types to create and analyze geometry values.

A geographic feature is anything in the world that has a location. A feature can be:

  • An entity. For example, a mountain, a pond, a city.

  • A space. For example, a postcode area, the tropics.

  • A definable location. For example, a crossroad, as a particular place where two streets intersect.

Some documents use the term geospatial feature to refer to geographic features.

Geometry is another word that denotes a geographic feature. Originally the word geometry meant measurement of the earth. Another meaning comes from cartography, referring to the geometric features that cartographers use to map the world.

This chapter uses all of these terms synonymously: geographic feature, geospatial feature, feature, or geometry. Here, the term most commonly used is geometry, defined as a point or an aggregate of points representing anything in the world that has a location.