Supported Spatial Operations

GeoETL provides 39 PostGIS-compatible spatial SQL functions powered by the GEOS library. These functions enable geometry manipulation, spatial analysis, and data transformation within your SQL queries.

Quick Reference

Category	Functions	Description
Construction	4	Create geometries from various input formats
Measurement	3	Measure distance, area, and length
Predicate	10	Test spatial relationships
Validator	5	Validate geometry properties
Generator	8	Generate new geometries
Set Operations	4	Combine geometries using set theory
Accessor	6	Extract geometry properties

All Functions

Construction Functions

Function	Description
ST_GeomFromText	Parse WKT string to geometry
ST_GeomFromWKB	Validate WKB binary data
ST_Point	Create point from X, Y coordinates
ST_MakePoint	Alias for ST_Point

Measurement Functions

Function	Description
ST_Distance	Calculate minimum distance between geometries
ST_Area	Calculate area of a geometry
ST_Length	Calculate length/perimeter of a geometry

Predicate Functions

Function	Description
ST_Intersects	Test if two geometries intersect
ST_Contains	Test if geometry A contains geometry B
ST_Within	Test if geometry A is within geometry B
ST_Overlaps	Test if two geometries overlap
ST_Touches	Test if geometries touch at boundaries
ST_Crosses	Test if geometries cross each other
ST_Disjoint	Test if geometries are disjoint
ST_Equals	Test if geometries are spatially equal
ST_Covers	Test if geometry A covers geometry B
ST_CoveredBy	Test if geometry A is covered by geometry B

Validator Functions

Function	Description
ST_IsValid	Test if geometry is valid (OGC rules)
ST_IsEmpty	Test if geometry is empty
ST_IsSimple	Test if geometry is simple
ST_IsClosed	Test if geometry is closed
ST_IsRing	Test if geometry is a ring

Generator Functions

Function	Description
ST_Buffer	Create buffer polygon around geometry
ST_Centroid	Calculate centroid point
ST_Envelope	Compute bounding box
ST_ConvexHull	Compute convex hull
ST_Boundary	Compute geometry boundary
ST_PointOnSurface	Get point guaranteed on surface
ST_Simplify	Douglas-Peucker simplification
ST_SimplifyPreserveTopology	Topology-preserving simplification

Set Operation Functions

Function	Description
ST_Union	Combine two geometries
ST_Intersection	Intersection of two geometries
ST_Difference	Difference of geometries (A - B)
ST_SymDifference	Symmetric difference (XOR)

Accessor Functions

Function	Description
ST_X	Get X coordinate of a Point
ST_Y	Get Y coordinate of a Point
ST_NumPoints	Count of points in geometry
ST_NumGeometries	Count of geometries in collection
ST_GeometryType	Get geometry type as string
ST_Dimension	Get topological dimension

Usage Examples

Basic Geometry Creation

SELECT ST_Point(longitude, latitude) as geom FROM locations;
SELECT ST_GeomFromText('POLYGON((0 0, 4 0, 4 4, 0 4, 0 0))') as polygon;

Spatial Analysis

-- Find all buildings within 100 meters of a point
SELECT * FROM buildings
WHERE ST_Distance(geom, ST_Point(-122.4, 37.8)) < 100;

-- Calculate total area by category
SELECT category, SUM(ST_Area(geom)) as total_area
FROM parcels
GROUP BY category;

Geometry Transformation

-- Create 50-meter buffer zones
SELECT id, ST_Buffer(geom, 50) as buffer FROM features;

-- Simplify complex geometries
SELECT id, ST_Simplify(geom, 0.001) as simplified FROM coastlines;

Spatial Filtering

-- Find intersecting features
SELECT a.id, b.id
FROM layer_a a, layer_b b
WHERE ST_Intersects(a.geom, b.geom);

-- Filter by containment
SELECT * FROM points
WHERE ST_Within(geom, (SELECT geom FROM boundaries WHERE name = 'Region A'));

Notes

• All functions use the GEOS library for computational geometry
• Input geometries can be in GeoArrow Point, WKB, or mixed geometry formats
• Output geometries are returned as WKB with geoarrow.wkb metadata
• NULL inputs return NULL outputs (SQL standard behavior)
• Functions are case-insensitive in SQL queries