ST_NUMPOINTS

Description

Returns the total number of vertices (points) in a geometry object. For different geometry types, the counting rules are as follows: a Point returns 1, a LineString returns the number of vertices, a Polygon returns the total number of vertices across all rings (including the closing point), and a MultiPolygon returns the sum of all sub-polygon point counts.

Syntax

ST_NUMPOINTS( <shape> )

Parameters

Parameter	Description
<shape>	The input geometry, of type GEOMETRY or VARCHAR (in WKT format) that can be converted to GEOMETRY.

Return Value

Returns a BIGINT value representing the total number of points in the geometry object.

ST_NUMPOINTS has the following edge cases:

• If the input parameter is NULL, returns NULL.
• If the input parameter cannot be parsed into a valid geometry object, returns NULL.
• For POINT, returns 1.
• For LINESTRING, returns the number of vertices in the line.
• For POLYGON, returns the total number of vertices across all rings (exterior ring + interior rings). Each ring includes the closing point.
• For MULTIPOLYGON, returns the sum of point counts of all sub-polygons.
• For CIRCLE, returns -1 (circles do not have discrete vertices).

Example

Number of points in a Point

SELECT ST_NUMPOINTS(ST_Point(1, 2));

+------------------------------+
| ST_NUMPOINTS(ST_Point(1, 2)) |
+------------------------------+
|                            1 |
+------------------------------+

Number of points in a LineString

SELECT ST_NUMPOINTS(ST_GeometryFromText('LINESTRING(0 0, 1 1, 2 2)'));

+-------------------------------------------------------------------+
| ST_NUMPOINTS(ST_GeometryFromText('LINESTRING(0 0, 1 1, 2 2)'))   |
+-------------------------------------------------------------------+
|                                                                 3 |
+-------------------------------------------------------------------+

Number of points in a Polygon (square)

SELECT ST_NUMPOINTS(ST_GeometryFromText('POLYGON((0 0, 1 0, 1 1, 0 1, 0 0))'));

+----------------------------------------------------------------------------+
| ST_NUMPOINTS(ST_GeometryFromText('POLYGON((0 0, 1 0, 1 1, 0 1, 0 0))'))  |
+----------------------------------------------------------------------------+
|                                                                          5 |
+----------------------------------------------------------------------------+

Number of points in a Polygon with a hole

SELECT ST_NUMPOINTS(ST_GeometryFromText('POLYGON((0 0, 10 0, 10 10, 0 10, 0 0),(1 1, 2 1, 2 2, 1 2, 1 1))'));

+-----------------------------------------------------------------------------------------------------------+
| ST_NUMPOINTS(ST_GeometryFromText('POLYGON((0 0, 10 0, 10 10, 0 10, 0 0),(1 1, 2 1, 2 2, 1 2, 1 1))'))   |
+-----------------------------------------------------------------------------------------------------------+
|                                                                                                        10 |
+-----------------------------------------------------------------------------------------------------------+

Number of points in a MultiPolygon

SELECT ST_NUMPOINTS(ST_GeometryFromText('MULTIPOLYGON(((0 0, 1 0, 1 1, 0 1, 0 0)),((2 2, 3 2, 3 3, 2 3, 2 2)))'));

+--------------------------------------------------------------------------------------------------------------+
| ST_NUMPOINTS(ST_GeometryFromText('MULTIPOLYGON(((0 0, 1 0, 1 1, 0 1, 0 0)),((2 2, 3 2, 3 3, 2 3, 2 2)))')) |
+--------------------------------------------------------------------------------------------------------------+
|                                                                                                           10 |
+--------------------------------------------------------------------------------------------------------------+

Number of points in a Circle (returns -1)

SELECT ST_NUMPOINTS(ST_Circle(0, 0, 100));

+--------------------------------------+
| ST_NUMPOINTS(ST_Circle(0, 0, 100))  |
+--------------------------------------+
|                                   -1 |
+--------------------------------------+

NULL Parameter

SELECT ST_NUMPOINTS(NULL);

+---------------------+
| ST_NUMPOINTS(NULL)  |
+---------------------+
|                NULL |
+---------------------+

Invalid Parameter (Returns NULL)

SELECT ST_NUMPOINTS(ST_GeometryFromText('INVALID'));

+------------------------------------------------+
| ST_NUMPOINTS(ST_GeometryFromText('INVALID'))   |
+------------------------------------------------+
|                                           NULL |
+------------------------------------------------+