PostGIS Aggregate Functions

The functions given below are spatial aggregate functions provided with PostGIS that can be used just like any other sql aggregate function such as sum, average.

• ST_Accum – Aggregate. Constructs an array of geometries.
• ST_Collect – Return a specified ST_Geometry value from a collection of other geometries.
• ST_Extent – an aggregate function that returns the bounding box that bounds rows of geometries.
• ST_Extent3D – an aggregate function that returns the box3D bounding box that bounds rows of geometries.
• ST_MakeLine – Creates a Linestring from point geometries.
• ST_MemUnion – Same as ST_Union, only memory-friendly (uses less memory and more processor time).
• ST_Polygonize – Aggregate. Creates a GeometryCollection containing possible polygons formed from the constituent linework of a set of geometries.
• ST_Union – Returns a geometry that represents the point set union of the Geometries.