Spatial (ST_* Functions)

With feature = "spatial", the crate exposes DuckDB’s spatial ST_* functions as typed Diesel DSL. Unlike the rest of the DSL, these are not in the dsl::* prelude — import them from better_duck_diesel::spatial::*. GEOMETRY values travel as WKB, so geometry arguments and results are typed Binary.

use better_duck_diesel::spatial::{ensure_loaded, st_point, st_as_text, st_distance};
use diesel::prelude::*;

ensure_loaded(&mut conn)?; // INSTALL + LOAD the spatial extension on demand
let wkt: String = diesel::select(st_as_text(st_point(1.0, 2.0))).get_result(&mut conn)?; // "POINT (1 2)"

Loading the extension

ensure_loaded(conn) installs and loads DuckDB’s spatial extension at runtime. Call it once per connection before using any ST_* function.

ensure_loaded returns Err when the extension cannot be made available — most often offline, because the install step needs network access unless the extension is already present. Handle the error gracefully (the crate’s own spatial tests skip rather than fail in that case). In a pool, run it from the on_connect hook so every connection is ready.

Functions

Function	Signature	Returns
`st_point(x, y)`	`Double, Double`	`Binary` (geometry/WKB)
`st_geom_from_text(wkt)`	`Text`	`Binary`
`st_as_text(geom)`	`Binary`	`Text`
`st_distance(a, b)`	`Binary, Binary`	`Double`
`st_area(geom)`	`Binary`	`Double`

use better_duck_diesel::spatial::{st_geom_from_text, st_area};

let a: f64 = diesel::select(
    st_area(st_geom_from_text("POLYGON((0 0, 0 1, 1 1, 1 0, 0 0))"))
).get_result(&mut conn)?; // 1.0

feature = "spatial" carries no extra Rust dependencies — it only gates this module. The ST_* functions are plain SQL and the geometry round-trips as WKB Binary.

Feature flags

What spatial enables.

Pooling

ensure_loaded per pooled connection.

Extensions (core)

Loading DuckDB extensions at the driver level.

DSL overview

The non-spatial DSL.

Getting Started

CRUD

DuckDB SQL DSL

Types & Pooling

Spatial (ST_* Functions)

Loading the extension

Functions

See also

Feature flags

Pooling

Extensions (core)

DSL overview

​Loading the extension

​Functions

​See also

Feature flags

Pooling

Extensions (core)

DSL overview

Loading the extension

Functions

See also