ST_union
Merges an array of pcpatch entries into a single pcpatch object.
Syntax
pcpatch ST_Union(pcpatch[] pcs);Parameters
| Parameter | Description |
|---|---|
pcs | The pcpatch array. |
Examples
The following example compares the total point count computed by aggregating patches first (ST_Union) against the sum of per-patch point counts (ST_NumPoints). Both queries return 100.
-- Compare npoints(sum(patches)) with sum(npoints(patches)).
SELECT ST_NumPoints(ST_Union(pa)) FROM patches;
SELECT Sum(ST_NumPoints(pa)) FROM patches;
100