POLYGON - CockroachDB

A POLYGON is a shape with a closed exterior that is made up of lines. Polygons can also contain holes. Polygons are often used to represent areas such as countries, states, or municipalities. The coordinates of each Point and line that make up the Polygon are translated according to the current (denoted by an ) to determine what the point “is”, or what it “means” relative to the (if any) in the data set. You can also store a “ with the following additional dimensions:

A third dimension coordinate Z (Z).
A measure coordinate M (M).
Both a third dimension and a measure coordinate (ZM).

The Z and M dimensions can be accessed or modified using a number of , including:

ST_Z
ST_M
ST_Affine
ST_Zmflag
ST_MakePoint
ST_MakePointM
ST_Force3D
ST_Force3DZ
ST_Force3DM
ST_Force4D
ST_Snap
ST_SnapToGrid
ST_RotateZ
ST_AddMeasure

Note that CockroachDB’s is still based on the 2D coordinate system. This means that:

The Z/M dimension is not index accelerated when using spatial predicates.
Some spatial functions ignore the Z/M dimension, with transformations discarding the Z/M value.

Examples

Well known text

A Polygon can be created from SQL by calling the st_geomfromtext function on a LineString definition expressed in the format as shown below.

SELECT ST_GeomFromText('POLYGON((0 0, 0 1024, 1024 1024, 1024 0, 0 0))');

                                                                                       st_geomfromtext
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
  010300000001000000050000000000000000000000000000000000000000000000000000000000000000009040000000000000904000000000000090400000000000009040000000000000000000000000000000000000000000000000
(1 row)

Polygons with holes

To represent a polygon with holes in , add one or more additional lists of coordinates that define the boundaries of the holes as shown below:

SELECT ST_GeomFromText('POLYGON((-87.906471 43.038902, -95.992775 36.153980, -75.704722 36.076944, -87.906471 43.038902), (-87.623177 41.881832, -90.199402 38.627003, -82.446732 38.413651, -87.623177 41.881832))');

                                                                                                                                           st_geomfromtext
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
  010300000002000000040000006FF1F09E03FA55C0DFDFA0BDFA844540545227A089FF57C0791EDC9DB513424064B14D2A1AED52C0CCCF0D4DD90942406FF1F09E03FA55C0DFDFA0BDFA84454004000000A4A7C821E2E755C07C48F8DEDFF0444073309B00C38C56C038BF61A241504340E884D041979C54C0967A1684F2344340A4A7C821E2E755C07C48F8DEDFF04440
(1 row)

Using a SQL function

You can also use the st_makepolygon function on a LineString that defines the outer boundary of the Polygon, e.g.:

SELECT ST_MakePolygon('LINESTRING(0 0, 0 1024, 1024 1024, 1024 0, 0 0)');

----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
  010300000001000000050000000000000000000000000000000000000000000000000000000000000000009040000000000000904000000000000090400000000000009040000000000000000000000000000000000000000000000000
(1 row)

​Examples

​Well known text

​Polygons with holes

​Using a SQL function

​See also

Examples

Well known text

Polygons with holes

Using a SQL function

See also