ST_Collect_Agg

Introduction: Collects all geometries in a geometry column into a single multi-geometry (MultiPoint, MultiLineString, MultiPolygon, or GeometryCollection). Unlike ST_Union_Agg, this function does not dissolve boundaries between geometries - it simply collects them into a multi-geometry.

Format: ST_Collect_Agg (A: geometryColumn)

Since: v1.8.1

SQL Example

SELECT ST_Collect_Agg(geom) FROM (
  SELECT ST_GeomFromWKT('POINT(1 2)') AS geom
  UNION ALL
  SELECT ST_GeomFromWKT('POINT(3 4)') AS geom
  UNION ALL
  SELECT ST_GeomFromWKT('POINT(5 6)') AS geom
)

Output:

MULTIPOINT ((1 2), (3 4), (5 6))

SQL Example with GROUP BY

SELECT category, ST_Collect_Agg(geom) FROM geometries GROUP BY category