Alias

Accum

Description

Constructs an array of geometries from a set of geometries.

ST_Accum is an aggregate function that return a single value, calculated from a set of values (a column or a subset of column values).

Coordinate Dimensions

2D	3D	M

Spatial Standards Support

Examples

--Creates an example table, and populates data there
create table "lines"(id serial PRIMARY KEY);
SELECT AddGeometryColumn ('lines','GEOM',25830,'LINESTRING',2);
INSERT INTO "lines" ("GEOM") VALUES (ST_GeomfromEWKT('SRID=25830;LINESTRING (1 1, 1 4, 1 7)'));
INSERT INTO "lines" ("GEOM") VALUES (ST_GeomfromEWKT('SRID=25830;LINESTRING (1 7, 3 7, 6 7)'));
INSERT INTO "lines" ("GEOM") VALUES (ST_GeomfromEWKT('SRID=25830;LINESTRING (6 7, 6 3, 6 1)'));

//SELECT DropGeometryTable ('lines');

PostgreSQL

--Return the Array of Geometries
SELECT ST_Accum("lines"."GEOM") from "lines";
SELECT c FROM (SELECT ST_Accum("lines"."GEOM") as c from "lines") as foo;

--Return a Subset of the Array
SELECT c[1:2] FROM (SELECT ST_Accum("lines"."GEOM") as c from "lines") as foo;

H2

--Return the Array of Geometries
SELECT (c) FROM (SELECT ST_AccumAgg("lines"."GEOM") as c from "lines") as foo ;
--Result
(0102000020e66400000300000000  ... 0000000000000f03f0000000000001c40, 
0102000020e664000003000000000  ... 000000000000018400000000000001c40, 
0102000020e664000003000000000  ... 400000000000001840000000000000f03f)

--Return a Subset of the Array
select (c) FROM (SELECT ST_AccumAgg("lines"."GEOM") as c from "lines" where id>2) as foo ;
--Result
(0102000020e664000003000000000 ... 000008400000000000001840000000000000f03f)

--Use the array as an argument for ST_MakeGeomColl
SELECT ST_AsText(ST_MakeGeomColl(c)) FROM (SELECT ST_AccumAgg("lines"."GEOM") as c from "lines") as foo;
--Result
GEOMETRYCOLLECTION (LINESTRING (1 1, 1 4, 1 7), LINESTRING (1 7, 3 7, 6 7), LINESTRING (6 7, 6 3, 6 1))

Related functions

ST_Collect