Introduction to Spatial Databases
Spatial databases store, query, and manipulate geographic data efficiently — they are the backbone of enterprise GIS and web mapping applications.
Theory & Foundations
Unlike file-based GIS, spatial databases enable multi-user access, spatial indexing, geometric operations, and integration with web services.
PostGIS extends PostgreSQL with spatial data types (geometry, geography), 300+ spatial functions (ST_Buffer, ST_Intersects, ST_Distance), and spatial indexing using GiST/R-tree.
SpatiaLite adds spatial capabilities to SQLite — a lightweight, file-based database ideal for embedded/mobile applications and single-user workflows.
Spatial queries combine location and attribute criteria: "Find all hospitals within 5km of the flood zone that have more than 100 beds." This is impossible with flat files.
Spatial indexing dramatically speeds up queries. Without an index, finding features within a polygon requires checking every feature. With R-tree index, only nearby features are checked.
In-Depth Coverage
PostGIS Essentials
The most powerful open-source spatial database extension.
- 300+ spatial functions for geometry operations
- ST_Buffer, ST_Intersects, ST_Contains, ST_Distance
- Supports SRID (spatial reference identifiers)
- Raster support with PostGIS Raster extension
- Integration with QGIS, GeoServer, web frameworks
Spatial SQL Examples
Common spatial queries demonstrate database power.
- Find points within polygon: ST_Within(point, polygon)
- Calculate distance: ST_Distance(geom_a, geom_b)
- Create buffer: ST_Buffer(geometry, distance)
- Find nearest: ORDER BY ST_Distance() LIMIT 1
- Spatial join: ST_Intersects(a.geom, b.geom)
Key Techniques
Data Visualization
- PostGIS: 55%
- Oracle Spatial: 20%
- SQL Server: 15%
- SpatiaLite: 10%
- 💾StoragePostGIS geometry/geography types
- ⚡IndexGiST R-tree for fast spatial queries
- 🔍QuerySQL + 300+ spatial functions
- 🌐ServeGeoServer, pg_tileserv, APIs
Practical Workflow
- Install PostgreSQL + PostGIS
- Create spatial database
- Import data using ogr2ogr or QGIS
- Create spatial indexes
- Write spatial SQL queries
- Connect QGIS to database
- Build views for common analyses
- Backup and maintain database
Software & Tools
Video Tutorials
Real-World Application
Real-World Projects
PostGIS stores 8B+ features.
Case Study
Problem-Based Learning
Environmental impact assessment for highway construction needs to identify affected schools.
Solution: Load highway centerline and school points into PostGIS. Run: SELECT s.name FROM schools s, highway h WHERE ST_DWithin(s.geom, h.geom, 1000);