---
id: duckdb/duckdb-skills/spatial
version: "3424f49b"
license: MIT
install: manual
updated: 2026-04-23
---

# spatial — Spatial handles geographic questions by combining DuckDB's spatial functions with Overture Maps, a free global dataset accessible via S3. Ask about nearby places, distances between points, or analyze your own GeoJSON, Shapefile, or GPX files—the skill manages spatial joins, containment checks, and format conversions.

Publisher: duckdb · Stars: 523 · Updated: 2026-04-23

Install (manual): `git clone https://github.com/duckdb/duckdb-skills`

## SKILL.md

You are answering spatial questions using DuckDB's spatial extension and, when needed, Overture Maps as a free global data source.

Question or file: `$0`
Additional context: `${1:-}`

## Step 1 — Understand what the user needs

Classify the question:

| Pattern | Data source | Key functions |
|---------|-------------|---------------|
| "Find X near Y" (no user file) | Overture Maps on S3 | `ST_Distance_Spheroid`, bbox filtering |
| "How far between A and B" | Geocode or user data | `ST_Distance_Spheroid` |
| "Which points fall inside polygons" | User files | `ST_Contains` |
| "Analyze this GeoJSON/Shapefile/GPX" | User file | `ST_Read`, measurement functions |
| "Show density/hotspots" | User or Overture data | H3 hex binning |
| "Convert to GeoJSON/GeoPackage" | User file | `COPY TO (FORMAT GDAL)` |
| "Count buildings/roads in area" | Overture Maps | bbox filtering + aggregation |

If the question involves real-world places, POIs, buildings, roads, or boundaries and the user hasn't provided a file, use **Overture Maps** — read `references/overture.md` for S3 paths and schema.

For spatial function syntax, read `references/functions.md`.

## Step 2 — Write and run the query

Always start with:
```sql
LOAD spatial;
SET geometry_always_xy = true;
```

Add extensions as needed:
- Overture/remote data: `LOAD httpfs; CREATE SECRET (TYPE S3, PROVIDER config, REGION 'us-west-2');`
- H3 hex binning: `INSTALL h3 FROM community; LOAD h3;`

### Key principles

**bbox filtering first** — When querying Overture, always filter on `bbox.xmin/xmax/ymin/ymax` before any spatial function. This uses Parquet predicate pushdown and avoids downloading the full dataset.

**Always set `geometry_always_xy = true`** — This ensures all spatial functions interpret coordinates as longitude, latitude (the standard for Overture, GeoJSON, and most data sources). Without it, spheroid functions assume latitude first and return wrong results.

**Use spheroid functions for real-world distances** — `ST_Distance_Spheroid` returns meters on the WGS84 ellipsoid. Plain `ST_Distance` uses planar coordinates and gives meaningless results for lat/lng. **Important:** spheroid functions (`ST_Distance_Spheroid`, `ST_Area_Spheroid`, etc.) require `POINT_2D` inputs, not generic `GEOMETRY`. Overture geometry columns are typed `GEOMETRY('OGC:CRS84')` and cannot be cast directly. Extract coordinates first:
```sql
ST_Point(ST_X(geometry), ST_Y(geometry))::POINT_2D
```

**CSV with lat/lng needs conversion** — `ST_Point(longitude, latitude)` (longitude first). This is the most common gotcha.

Run the query in a single bash call:

```bash
duckdb -c "
LOAD spatial;
<ADDITIONAL_SETUP>
<YOUR_QUERY>
"
```

## Step 3 — Present results

- For tabular results: show the data directly
- For spatial results: consider exporting to GeoJSON for visualization (`COPY TO 'result.geojson' WITH (FORMAT GDAL, DRIVER 'GeoJSON')`)
- For distance/area results: use human-readable units (km for large distances, m for small)
- For density/hotspot results: describe the pattern and offer to export for visualization

If the query fails:
- **`duckdb: command not found`** → delegate to `/duckdb-skills:install-duckdb`
- **Missing extension** → `INSTALL spatial; LOAD spatial;` or `INSTALL h3 FROM community; LOAD h3;`
- **S3 access denied** → suggest checking AWS credentials
- **No results with Overture** → widen the bbox, check the category spelling, or try a broader search


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