Amazon Redshift will no longer support the creation of new Python UDFs starting Patch 198. Existing Python UDFs will continue to function until June 30, 2026. For more information, see the [ blog post ](https://aws.amazon.com/blogs/big-data/amazon-redshift-python-user-defined-functions-will-reach-end-of-support-after-june-30-2026/). 

# ST\$1IsClosed
<a name="ST_IsClosed-function"></a>

ST\$1IsClosed returns true if the 2D projection of the input geometry is closed. The following rules define a closed geometry: 
+ The input geometry is a point or a multipoint. 
+ The input geometry is a linestring, and the start and end points of the linestring coincide. 
+ The input geometry is a nonempty multilinestring and all its linestrings are closed. 
+ The input geometry is a nonempty polygon, all polygon's rings are nonempty, and the start and end points of all its rings coincide. 
+ The input geometry is a nonempty multipolygon and all its polygons are closed.
+ The input geometry is a nonempty geometry collection and all its components are closed. 

## Syntax
<a name="ST_IsClosed-function-syntax"></a>

```
ST_IsClosed(geom)
```

## Arguments
<a name="ST_IsClosed-function-arguments"></a>

 *geom*   
A value of data type `GEOMETRY` or an expression that evaluates to a `GEOMETRY` type. 

## Return type
<a name="ST_IsClosed-function-return"></a>

`BOOLEAN`

If *geom* is an empty point, then false is returned. 

If *geom* is null, then null is returned. 

## Examples
<a name="ST_IsClosed-function-examples"></a>

The following SQL checks if the polygon is closed. 

```
SELECT ST_IsClosed(ST_GeomFromText('POLYGON((0 2,1 1,0 -1,0 2))'));
```

```
st_isclosed
-----------
 true
```