# s2
Our S2 module is based on a port of the official S2 geometry library created by Google. For more information about S2 check the [library's website](http://s2geometry.io/) or the [Spatial Indexes section](https://docs.carto.com/data-and-analysis/analytics-toolbox-for-snowflake/key-concepts/spatial-indexes#s2) of this documentation.
## S2\_BOUNDARY
```sql
S2_BOUNDARY(id)
```
**Description**
Returns the boundary for a given S2 cell ID. We extract the boundary by getting the corner longitudes and latitudes, then enclose it in a GeoJSON and finally transform it into geography.
**Input parameters**
* `id`: `BIGINT` S2 cell ID to get the boundary geography from.
**Return type**
`GEOGRAPHY`
**Example**
```sql
SELECT CARTO.CARTO.S2_BOUNDARY(955378847514099712);
-- { "coordinates": [ [ [ -3.743508991266907, 40.24850114133136 ], [ -3.743508991266907, 40.57421345060903 ] ...
```
{% hint style="info" %}
S2 Cell edges are spherical geodesics.
{% endhint %}
## S2\_FROMGEOGPOINT
```sql
S2_FROMGEOGPOINT(point, resolution)
```
**Description**
Returns the S2 cell ID of a given point at a requested resolution.
**Input parameters**
* `point`: `GEOGRAPHY` point to get the ID from.
* `resolution`: `INT` level of detail or zoom.
**Return type**
`BIGINT`
**Example**
```sql
SELECT CARTO.CARTO.S2_FROMGEOGPOINT(ST_POINT(-3.7038, 40.4168), 8);
-- 955378847514099712
```
## S2\_FROMHILBERTQUADKEY
```sql
S2_FROMHILBERTQUADKEY(hquadkey)
```
**Description**
Returns the conversion of a Hilbert quadkey (a.k.a Hilbert curve quadtree ID) into a S2 cell ID.
**Input parameters**
* `hquadkey`: `STRING` Hilbert quadkey to be converted.
**Return type**
`BIGINT`
**Example**
```sql
SELECT CARTO.CARTO.S2_FROMHILBERTQUADKEY('0/12220101');
-- 955378847514099712
```
## S2\_FROMLONGLAT
```sql
S2_FROMLONGLAT(longitude, latitude, resolution)
```
**Description**
Returns the S2 cell ID for a given longitude, latitude and zoom resolution.
**Input parameters**
* `longitude`: `DOUBLE` horizontal coordinate on the map.
* `latitude`: `DOUBLE` vertical coordinate on the map.
* `resolution`: `INT` level of detail or zoom.
**Return type**
`BIGINT`
**Example**
```sql
SELECT CARTO.CARTO.S2_FROMLONGLAT(-3.7038, 40.4168, 8);
-- 955378847514099712
```
## S2\_TOHILBERTQUADKEY
```sql
S2_TOHILBERTQUADKEY(id)
```
**Description**
Returns the conversion of a S2 cell ID into a Hilbert quadkey (a.k.a Hilbert curve quadtree ID).
**Input parameters**
* `id`: `BIGINT` S2 cell ID to be converted.
**Return type**
`STRING`
**Example**
```sql
SELECT CARTO.CARTO.S2_TOHILBERTQUADKEY(955378847514099712);
-- 0/12220101
```