Lightstream – Arrow IPC streaming without compromise

Why this crate exists

When building high-performance, full-stack, data-driven applications, I repeatedly hit the same barriers.

• Protobuf/gRPC: convenient, but introduces memory copies.
• FlightRPC: powerful, but heavyweight and overengineered for most cases.

I wanted a crate that would:

1. Integrate Arrow IPC memory format seamlessly into any async context
2. Provide low-level control
3. Establish composable patterns for arbitrary wire formats
4. Require no heavy infrastructure to get started
5. Offer a true zero-copy path from wire -> SIMD kernels without re-allocation
6. Maintain reasonable compile times

Lightstream is the result: an extension to Minarrow that adds native streaming and I/O. It enables raw bytestream construction, reading and writing IPC and TLV formats, CSV/Parquet writers, and a high-performance 64-byte SIMD memory-mapped IPC reader.

Use cases

• Bypassing library machinery and going straight to the wire
• Streaming Arrow IPC tables over network sockets with zero-copy buffers
• Defining custom binary transport protocols
• Zero-copy ingestion with mmap for ultra-fast analytics
• Control data alignment at source - SIMD-aligned Arrow IPC writers/readers
• Async data pipelines with backpressure-aware sinks and streams
• Building custom data transport layers and transfer protocols

Introduction

Lightstream provides composable building blocks for high-performance data I/O in Rust:

• Asynchronous Arrow IPC streaming and file writing
• Framed decoders/sinks for IPC, TLV, CSV, and optional Parquet
• Zero-copy, memory-mapped Arrow file reads (~4.5ms for 100M rows × 4 columns on a consumer laptop)
• Direct integration with Tokio and futures using zero-copy buffers
• 64-byte SIMD aligned readers/writers (the only Arrow-compatible crate providing this in 2025)

Design Principles

• Customisable – You own the buffer. Pull-based or sink-driven streaming.
• Composable – Layerable codecs for encoders, decoders, sinks, and stream adapters.
• Control – Wire-level framing: IPC, TLV, CSV, and Parquet are handled at the transport boundary.
• Compatible – Native async support for futures and Tokio.
• Power – 64-byte aligned memory via Vec64 ensures deterministic SIMD without hot-loop re-allocations.
• Extensible – Primitive building blocks to implement custom wire formats. Contributions welcome.
• Efficient – Minimal dependencies and fast compile times.

Layered Abstractions

Each layer is trait-based with a reference implementation. Swap in your own framing, buffering, or encoding logic without re-implementing the stack.

Supported Formats

• Arrow IPC – Full support for SIMD-aligned File and Stream protocols, schema + dictionaries, streaming or random access.
• TLV – Minimal type-length-value framing for telemetry, control, or lightweight transport.
• Parquet (feature-gated) – Compact, columnar, compression-aware writer (Zstd, Snappy) with minimal dependencies.
• CSV – Streaming Arrow/Minarrow table readers/writers with headers, nulls, and custom delimiter/null handling.
• Memory Maps – Ultra-fast, zero-copy ingestion: millions of rows in microseconds, SIMD-ready.

Examples

Framed Stream Reader

use lightstream::models::streams::framed_byte_stream::FramedByteStream;
use lightstream::models::decoders::ipc::table_stream::TableStreamDecoder;
use lightstream::models::readers::ipc::table_stream_reader::TableStreamReader;

let framed = FramedByteStream::new(socket, TableStreamDecoder::default());
let mut reader = TableStreamReader::new(framed);

while let Some(table) = reader.next_table().await? {
    println!("Received table: {:?}", table.name);
}

Custom Protocol

pub struct MyFramer;

impl FrameDecoder for MyFramer {
    type Frame = Vec<u8>;
    fn decode(&mut self, buf: &[u8]) -> DecodeResult<Self::Frame> {
        // Custom framing logic
    }
}

let stream = FramedByteStream::new(socket, MyFramer);

Write Tables

use minarrow::{arr_i32, arr_str32, FieldArray, Table};
use lightstream::table_writer::TableWriter;
use lightstream::enums::IPCMessageProtocol;
use tokio::fs::File;

#[tokio::main]
async fn main() -> std::io::Result<()> {
    let col1 = FieldArray::from_inner("numbers", arr_i32![1, 2, 3]);
    let col2 = FieldArray::from_inner("letters", arr_str32!["x", "y", "z"]);
    let table = Table::new("demo".into(), vec![col1, col2].into());

    let file = File::create("demo.arrow").await?;
    let schema = table.schema().to_vec();
    let mut writer = TableWriter::new(file, schema, IPCMessageProtocol::File)?;

    writer.write_table(table).await?;
    writer.finish().await?;
    Ok(())
}

Optional Features

• parquet – Parquet writer
• mmap – Memory-mapped files
• zstd – Zstd compression (IPC + Parquet)
• snappy – Snappy compression (IPC + Parquet)

Licence

This project is licensed under the MIT Licence. See the LICENCE file for full terms, and THIRD_PARTY_LICENSES for Apache-licensed dependencies.

Affiliation Notice

This project is not affiliated with Apache Arrow or the Apache Software Foundation.
It serialises the public Arrow format via a custom implementation (Minarrow), while reusing Flatbuffers schemas from Arrow-RS for schema type generation.