A MULTIPOLYGON is a collection of Polygons. MultiPolygons are useful for gathering a group of Polygons into one geometry. For example, you may want to gather the Polygons denoting a group of properties in a particular municipality. Another use of MultiPolygons is to represent states or countries that include islands, or that are otherwise made up of non-overlapping shapes.
You can also store a MULTIPOLYGON with the following additional dimensions:
- A third dimension coordinate
Z(MULTIPOLYGONZ). - A measure coordinate
M(MULTIPOLYGONM). - Both a third dimension and a measure coordinate (
MULTIPOLYGONZM).
The Z and M dimensions can be accessed or modified using a number of built-in functions, including:
ST_ZST_MST_AffineST_ZmflagST_MakePointST_MakePointMST_Force3DST_Force3DZST_Force3DMST_Force4DST_SnapST_SnapToGridST_RotateZST_AddMeasure
Note that CockroachDB's spatial indexing 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 MultiPolygon can be created from SQL by calling the st_geomfromtext function on a MultiPolygon definition expressed in the Well Known Text (WKT) format.
SELECT ST_GeomFromText('SRID=4326;MULTIPOLYGON(((-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), (-84.191605 39.758949, -75.165222 39.952583, -78.878738 42.880230, -84.191605 39.758949)))');
st_geomfromtext
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0106000020E610000001000000010300000003000000040000006FF1F09E03FA55C0DFDFA0BDFA844540545227A089FF57C0791EDC9DB513424064B14D2A1AED52C0CCCF0D4DD90942406FF1F09E03FA55C0DFDFA0BDFA84454004000000A4A7C821E2E755C07C48F8DEDFF0444073309B00C38C56C038BF61A241504340E884D041979C54C0967A1684F2344340A4A7C821E2E755C07C48F8DEDFF044400400000001309E41430C55C07C2AA73D25E143401AA54BFF92CA52C0DFDC5F3DEEF9434028F04E3E3DB853C0A27A6B60AB70454001309E41430C55C07C2AA73D25E14340
(1 row)
See also
- Spatial tutorial
- Spatial objects
- POINT
- LINESTRING
- POLYGON
- MULTIPOINT
- MULTILINESTRING
- GEOMETRYCOLLECTION
- Using GeoServer with CockroachDB
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