serde_arrow - convert sequences of Rust objects to Arrow arrays and back again

Crate info | API docs | Example | Related packages & performance | Status | License | Changes | Contributing

The Arrow in-memory format is a powerful way to work with data-frame-like structures. The surrounding ecosystem includes a rich set of libraries, ranging from data frames such as Polars to query engines such as DataFusion. However, the API of the underlying Rust crates can be at times cumbersome to use due to the statically typed nature of Rust.

serde_arrow offers a simple way to convert Rust objects into Arrow arrays and back. serde_arrow relies on the Serde package to interpret Rust objects. Therefore, adding support for serde_arrow to custom types is as easy as using Serde's derive macros.

serde_arrow supports arrow for schema tracing, serialization from Rust structs to arrays, and deserialization from arrays to Rust structs.

Monorepo

This repository also contains marrow, the minimal Arrow interop crate used by serde_arrow. See marrow/Changes.md for its changelog. The crates are versioned and released independently with crate-scoped tags such as marrow/v1.0.0 and serde_arrow/v1.0.0.

Example

The following examples assume that serde_arrow is added to the Cargo.toml file and its features are configured. serde_arrow supports different arrow versions. The relevant one can be selected by specifying the correct feature (e.g., arrow-53 to support arrow=53). See here for more details.

The following examples use this Rust structure and example records:

#[derive(Serialize, Deserialize)]
struct Record {
    a: f32,
    b: i32,
}

let records = vec![
    Record { a: 1.0, b: 1 },
    Record { a: 2.0, b: 2 },
    Record { a: 3.0, b: 3 },
];

Serialize to arrow RecordBatch

use arrow::datatypes::FieldRef;
use serde_arrow::schema::{SchemaLike, TracingOptions};

// Determine Arrow schema
let fields = Vec::<FieldRef>::from_type::<Record>(TracingOptions::default())?;

// Build a record batch
let batch = serde_arrow::to_record_batch(&fields, &records)?;

This RecordBatch can now be written to disk using ArrowWriter from the parquet crate.

use parquet::arrow::ArrowWriter;

let file = File::create("example.pq")?;
let mut writer = ArrowWriter::try_new(file, batch.schema(), None)?;
writer.write(&batch)?;
writer.close()?;

Usage from Python

The written files can be read in Python via

# using polars
>>> import polars as pl
>>> pl.read_parquet("example.pq")
shape: (3, 2)
┌─────┬─────┐
│ a   ┆ b   │
│ --- ┆ --- │
│ f32 ┆ i32 │
╞═════╪═════╡
│ 1.0 ┆ 1   │
│ 2.0 ┆ 2   │
│ 3.0 ┆ 3   │
└─────┴─────┘

# using pandas
>>> import pandas as pd
>>> pd.read_parquet("example.pq")
     a  b
0  1.0  1
1  2.0  2
2  3.0  3

Related packages & Performance

• arrow: the JSON component of the official Arrow package supports serializing objects via the Decoder. It supports primitive types, structs, and lists
• arrow-convert: a derive-based converter for arrow-rs
• typed-arrow: derive-based converter of Rust structs to Arrow

The different implementations have the following performance differences compared to direct Arrow builder construction. These benchmark results are workload-specific and only indicative.

The detailed runtimes of the benchmarks are listed below.

complex_1000

label	time [ms]	arrow builder	serde_arrow::to	serde_arrow::to	arrow_json::Rea
arrow builder	0.36	1.00	0.21	0.18	0.12
serde_arrow::to_arrow	1.74	4.86	1.00	0.87	0.59
serde_arrow::to_marrow	2.00	5.58	1.15	1.00	0.68
arrow_json::ReaderBuilder	2.97	8.27	1.70	1.48	1.00

primitives_1000

label	time [ms]	arrow builder	serde_arrow::to	serde_arrow::to	arrow_json::Rea
arrow builder	0.05	1.00	0.10	0.10	0.06
serde_arrow::to_marrow	0.49	10.42	1.00	0.99	0.58
serde_arrow::to_arrow	0.50	10.51	1.01	1.00	0.59
arrow_json::ReaderBuilder	0.85	17.89	1.72	1.70	1.00

License

Copyright (c) 2021 - 2026 Christopher Prohm and contributors

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.