GeoParquet Batch Writer

Rust library (plus derive macro) for writing GeoParquet files efficiently in batches using GeoArrow/Arrow. Define a simple row struct with a geometry field, derive GeoParquetRowData, and stream rows to an on-disk GeoParquet file.

Features

• Derive macro to turn your struct into Arrow arrays + schema
• Automatic batching with a configurable max_rows_per_batch
• Supports geo-types: Point, LineString, Polygon, MultiPoint, MultiLineString, MultiPolygon, Geometry, GeometryCollection (all f64)
• Optional fields via Option<T> (including optional geometry)
• Column rename and geometry dimension hints (XY/XYZ/XYM)

Workspace layout

• crates/core: library crate geoparquet-batch-writer
• crates/derive: proc-macro crate exporting #[derive(GeoParquetRowData)]
• crates/example-cli: example CLI demonstrating how to generate random data and write GeoParquet using the library (not published)

Build

• Prereqs: Rust (stable) with Cargo

# build the workspace (library + derive + example CLI)
cargo build -q

# run tests (core crate has unit tests)
cargo test -q

Library usage

cargo add geoparquet-batch-writer

Add a row type and derive GeoParquetRowData. Mark exactly one geometry field with #[geo(geometry)]. Optionally rename columns or set geometry dimension.

use anyhow::Result;
use geo_types::Point;
use geoparquet_batch_writer::{BatchConfig, GeoParquetBatchWriter, GeoParquetRowData};

#[derive(GeoParquetRowData)]
struct Row {
    id: u64,
    #[geo(name = "geom", geometry, dim = "XY")] // XY | XYZ | XYM
    point: Point<f64>,
    note: Option<String>,
}

fn main() -> Result<()> {
    let mut w: GeoParquetBatchWriter<Row> = GeoParquetBatchWriter::new(
        "output.parquet",
        Default::default(),
    )?;

    for i in 0..25_000u64 {
        w.add_row(Row {
            id: i,
            point: Point::new(-120.0 + (i as f64 * 0.0001), 35.0),
            note: (i % 2 == 0).then(|| format!("row {i}")),
        })?;
    }

    w.finish()?; // flush remaining, write metadata, close file
    Ok(())
}

Notes

• Only one geometry field is supported per row at the moment
• Geometry can be optional (Option<Point<f64>>) and will produce nulls
• Non-geometry columns support typical Arrow scalar types (e.g., integers, floats, strings)

Example CLI

An example CLI lives in crates/example-cli to illustrate how to consume the library. It is for demonstration only and is not published to crates.io.

Run it like this:

# from repo root
cargo run -q -p geoparquet-batch-writer-example-cli -- \
    --output output.parquet \
    --count 10000 \
    --bbox "-180,-90,180,90"

Flags

• --output (path): where to write the GeoParquet file (default output.parquet)
• --count (usize): number of random points (default 10000)
• --bbox (min_lon,min_lat,max_lon,max_lat): bounding box for random points (default -180,-90,180,90)