PostGIS

ST_MemUnion

Prev

8.13. Overlay Functions

Next

Name

ST_MemUnion — Aggregate function which unions geometries in a memory-efficent but slower way

Synopsis

geometry +`*`+ST_MemUnion*(`geometry set `geomfield`)`;

Description

An aggregate function that unions the input geometries, merging them to produce a result geometry with no overlaps. The output may be a single geometry, a MultiGeometry, or a Geometry Collection.

Note

Produces the same result as ST_Union, but uses less memory and more processor time. This aggregate function works by unioning the geometries incrementally, as opposed to the ST_Union aggregate which first accumulates an array and then unions the contents using a fast algorithm.

check This function supports 3d and will not drop the z-index. However, the result is computed using XY only. The result Z values are copied, averaged or interpolated.

Examples

SELECT id,
       ST_MemUnion(geom) as singlegeom
FROM sometable f
GROUP BY id;

See Also

ST_Union

Prev

Up

Next

ST_Intersection

Home

ST_Node