LINESTRING

A LINESTRING is a collection of that are “strung together” into one geometric object. A LineString can be used to represent an arbitrary curve, such as a Bézier curve. In practice, this means that LineStrings are useful for representing real-world objects such as roads and rivers.

The coordinates of each Point that makes up the LineString 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 LINESTRING with the following additional dimensions:

• A third dimension coordinate Z ( LINESTRINGZ ).
• A measure coordinate M ( LINESTRINGM ).
• Both a third dimension and a measure coordinate ( LINESTRINGZM ).

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

A LineString 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('LINESTRING(0 0, 1440 900)');

                                   st_geomfromtext
--------------------------------------------------------------------------------------
  0102000000020000000000000000000000000000000000000000000000008096400000000000208C40
(1 row)

You can also make a LineString using the of st_makeline.

See also