> ## Documentation Index
> Fetch the complete documentation index at: https://docs.cockroachlabs.com/llms.txt
> Use this file to discover all available pages before exploring further.

# MULTILINESTRING

A `MULTILINESTRING` is a collection of [LineStrings](/docs/stable/linestring.md).  MultiLineStrings are useful for gathering a group of LineStrings into one geometry. For example, you may want to gather the LineStrings denoting all of the roads in a particular municipality.

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 [built-in functions](/docs/stable/functions-and-operators.md#spatial-functions), 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 [spatial indexing](/docs/stable/spatial-indexes.md) 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 MultiLineString can be created from SQL by calling the `st_geomfromtext` function on a MultiLineString definition expressed in the [Well Known Text (WKT)](/docs/stable/architecture/glossary.md#wkt) format.

```sql theme={"theme":{"light":"catppuccin-mocha","dark":"catppuccin-mocha"}}
SELECT ST_GeomFromText('MULTILINESTRING((0 0, 1440 900), (800 600, 200 400))');
```

```
                                                                                     st_geomfromtext
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
  0105000000020000000102000000020000000000000000000000000000000000000000000000008096400000000000208C4001020000000200000000000000000089400000000000C0824000000000000069400000000000007940
(1 row)
```

### SQL

A MultiLineString can be created from SQL by calling an aggregate function such as `ST_Collect` or [`ST_Union`](/docs/stable/st_union) on a column that contains [LineString](/docs/stable/linestring.md) geometries.  In the example below, we will build a MultiLineString from several LineStrings.

1. Insert the LineStrings:

   ```sql theme={"theme":{"light":"catppuccin-mocha","dark":"catppuccin-mocha"}}
   CREATE TABLE tmp_linestrings (id INT8 default unique_rowid(), geom GEOMETRY);

   INSERT INTO tmp_linestrings (geom)
   VALUES
   (st_geomfromtext('SRID=4326;LINESTRING(-88.243385 40.116421, -87.906471 43.038902, -95.992775 36.153980)')),
   (st_geomfromtext('SRID=4326;LINESTRING(-75.704722 36.076944, -95.992775 36.153980, -87.906471 43.038902)')),
   (st_geomfromtext('SRID=4326;LINESTRING(-76.8261 42.1727,  -75.6608 41.4102,-73.5422 41.052, -73.929 41.707,  -76.8261 42.1727)'));
   ```

2. Build a MultiLineString from the individual [LineStrings](/docs/stable/linestring.md) using `ST_Collect`, and check the output with `ST_GeometryType` to verify that it is indeed a MultiLineString:

   ```sql theme={"theme":{"light":"catppuccin-mocha","dark":"catppuccin-mocha"}}
   SELECT ST_GeometryType(st_collect(geom)) AS output FROM tmp_linestrings;
   ```

   ```
           output
   ----------------------
     ST_MultiLineString
   (1 row)
   ```

3. Drop the temporary table:

   ```sql theme={"theme":{"light":"catppuccin-mocha","dark":"catppuccin-mocha"}}
   DROP TABLE tmp_linestrings;
   ```

## See also

* [Spatial objects](/docs/stable/spatial-data-overview.md#spatial-objects)
* [POINT](/docs/stable/point.md)
* [LINESTRING](/docs/stable/linestring.md)
* [POLYGON](/docs/stable/polygon.md)
* [MULTIPOINT](/docs/stable/multipoint.md)
* [MULTIPOLYGON](/docs/stable/multipolygon.md)
* [GEOMETRYCOLLECTION](/docs/stable/geometrycollection.md)