POINT

A POINT is a sizeless location identified by its X and Y coordinates. These coordinates are then 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

SQL

A Point can be created in SQL by the st_point function.

The statement below creates a Point (using the common ).

SELECT ST_SetSRID(ST_Makepoint(0,0), 4326);

                      st_setsrid
------------------------------------------------------
  0101000020E610000000000000000000000000000000000000
(1 row)

Well known text

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

SELECT ST_GeomFromText('POINT(0 0)');

               st_geomfromtext
----------------------------------------------
  010100000000000000000000000000000000000000
(1 row)

See also