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/). 

# H3\$1Polyfill
<a name="H3_Polyfill-function"></a>

H3\$1Polyfill returns the corresponding H3 cell IDs that correspond to the hexagons and pentagons that are contained in the input polygon of the given resolution. For information about H3 indexing, see [H3](spatial-terminology.md#spatial-terminology-h3).

## Syntax
<a name="H3_Polyfill-function-syntax"></a>

```
H3_Polyfill(geom, resolution)
```

## Arguments
<a name="H3_Polyfill-function-arguments"></a>

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

 *resolution*   
A value of data type `INTEGER` or an expression that evaluates to an `INTEGER` type. The value represents the resolution of the H3 grid system. The value must be an integer between 0–15, inclusive. With `0` being the coarsest and `15` being the finest. 

## Return type
<a name="H3_Polyfill-function-return"></a>

`SUPER` – represents a list of H3 cell IDs.

If *geom* is not a `POLYGON`, then an error is returned.

If *resolution* is out of bounds, then an error is returned.

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

## Examples
<a name="H3_Polyfill-function-examples"></a>

The following SQL returns a SUPER data type array of H3 cell IDs from a polygon and resolution `4`. 

```
SELECT H3_Polyfill(ST_GeomFromText('POLYGON((0 0, 0 1, 1 1, 1 0, 0 0))'), 4);
```

```
 h3_polyfill
----------------------------------------------------------------------------------------------------------------------------------------------------------
 [596538848238895103,596538805289222143,596538856828829695,596538813879156735,596537920525959167,596538685030137855,596538693620072447,596538839648960511]
```