Amazon Redshift will no longer support the use of Python UDFs after June 30, 2026. We will start enforcing it in phases. For more information on the details of Python end of life and migration options, 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/) that was published on June 30, 2025. 

# ST\_ZMax
<a name="ST_ZMax-function"></a>

ST\_ZMax 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
```