chDB for Rust

chDB-rust provides experimental FFI (Foreign Function Interface) bindings for chDB, enabling you to run ClickHouse queries directly in your Rust applications with zero external dependencies.

Installation

Install libchdb

Install the chDB library:

curl -sL https://lib.chdb.io | bash

Usage

chDB Rust provides both stateless and stateful query execution modes.

Stateless usage

For simple queries without persistent state:

use chdb_rust::{execute, arg::Arg, format::OutputFormat};

fn main() -> Result<(), Box<dyn std::error::Error>> {
    // Execute a simple query
    let result = execute(
        "SELECT version()",
        Some(&[Arg::OutputFormat(OutputFormat::JSONEachRow)])
    )?;
    println!("ClickHouse version: {}", result.data_utf8()?);
    
    // Query with CSV file
    let result = execute(
        "SELECT * FROM file('data.csv', 'CSV')",
        Some(&[Arg::OutputFormat(OutputFormat::JSONEachRow)])
    )?;
    println!("CSV data: {}", result.data_utf8()?);
    
    Ok(())
}

Stateful usage (Sessions)

For queries requiring persistent state like databases and tables:

use chdb_rust::{
    session::SessionBuilder,
    arg::Arg,
    format::OutputFormat,
    log_level::LogLevel
};
use tempdir::TempDir;

fn main() -> Result<(), Box<dyn std::error::Error>> {
    // Create a temporary directory for database storage
    let tmp = TempDir::new("chdb-rust")?;
    
    // Build session with configuration
    let session = SessionBuilder::new()
        .with_data_path(tmp.path())
        .with_arg(Arg::LogLevel(LogLevel::Debug))
        .with_auto_cleanup(true)  // Cleanup on drop
        .build()?;

    // Create database and table
    session.execute(
        "CREATE DATABASE demo; USE demo", 
        Some(&[Arg::MultiQuery])
    )?;

    session.execute(
        "CREATE TABLE logs (id UInt64, msg String) ENGINE = MergeTree() ORDER BY id",
        None,
    )?;

    // Insert data
    session.execute(
        "INSERT INTO logs (id, msg) VALUES (1, 'Hello'), (2, 'World')",
        None,
    )?;

    // Query data
    let result = session.execute(
        "SELECT * FROM logs ORDER BY id",
        Some(&[Arg::OutputFormat(OutputFormat::JSONEachRow)]),
    )?;

    println!("Query results:\n{}", result.data_utf8()?);
    
    // Get query statistics
    println!("Rows read: {}", result.rows_read());
    println!("Bytes read: {}", result.bytes_read());
    println!("Query time: {:?}", result.elapsed());

    Ok(())
}

Building and testing

Build the project

cargo build

Run tests

cargo test

Development dependencies

The project includes these development dependencies:

• bindgen (v0.70.1) - Generate FFI bindings from C headers
• tempdir (v0.3.7) - Temporary directory handling in tests
• thiserror (v1) - Error handling utilities

Error handling

chDB Rust provides comprehensive error handling through the Error enum:

use chdb_rust::{execute, error::Error};

match execute("SELECT 1", None) {
    Ok(result) => {
        println!("Success: {}", result.data_utf8()?);
    },
    Err(Error::QueryError(msg)) => {
        eprintln!("Query failed: {}", msg);
    },
    Err(Error::NoResult) => {
        eprintln!("No result returned");
    },
    Err(Error::NonUtf8Sequence(e)) => {
        eprintln!("Invalid UTF-8: {}", e);
    },
    Err(e) => {
        eprintln!("Other error: {}", e);
    }
}

GitHub repository

You can find the GitHub repository for the project at chdb-io/chdb-rust.