docs/api/sql/Bounding-Box-Functions/ST_Expand.md

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# ST_Expand

Introduction: Returns a geometry expanded from the bounding box of the input. The expansion can be specified in two ways:

1. By individual axis using `deltaX`, `deltaY`, or `deltaZ` parameters.
2. Uniformly across all axes using the `uniformDelta` parameter.

!!!Note
    Things to consider when using this function:

    1. The `uniformDelta` parameter expands Z dimensions for XYZ geometries; otherwise, it only affects XY dimensions.
    2. For XYZ geometries, specifying only `deltaX` and `deltaY` will preserve the original Z dimension.
    3. If the input geometry has an M dimension then using this function will drop the said M dimension.

![ST_Expand](../../../image/ST_Expand/ST_Expand.svg "ST_Expand")

Format:

`ST_Expand(geometry: Geometry, uniformDelta: Double)`

`ST_Expand(geometry: Geometry, deltaX: Double, deltaY: Double)`

`ST_Expand(geometry: Geometry, deltaX: Double, deltaY: Double, deltaZ: Double)`

Return type: `Geometry`

Since: `v1.6.1`

SQL Example:

```sql
SELECT ST_Expand(
        ST_GeomFromWKT('POLYGON Z((50 50 1, 50 80 2, 80 80 3, 80 50 2, 50 50 1))'),
        10
   )
```

Output:

```
POLYGON Z((40 40 -9, 40 90 -9, 90 90 13, 90 40 13, 40 40 -9))
```