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\$1ZMax
<a name="ST_ZMax-function"></a>

ST\$1ZMax returns the maximum `z` coordinate of an input geometry. 

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

```
ST_ZMax(geom)
```

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

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

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

`DOUBLE PRECISION` value of the maximum `z` coordinate.

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

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

If *geom* is a 2D or 3DM geometry, then null is returned. 

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

The following SQL returns the largest `z` coordinate of a linestring in a 3DZ geometry. 

```
SELECT ST_ZMax(ST_GeomFromEWKT('LINESTRING Z (0 1 2, 3 4 5, 6 7 8)'));
```

```
st_zmax
-----------
  8
```

The following SQL returns the largest `z` coordinate of a linestring in a 4D geometry. 

```
SELECT ST_ZMax(ST_GeomFromEWKT('LINESTRING ZM (0 1 2 3, 4 5 6 7, 8 9 10 11)'));
```

```
st_zmax
-----------
  10
```