Sled, the Fast and Lightweight Rust Database

Sled vs SQL vs Other Rust DB Crates (RocksDB, SeaORM, Rbatis)

---

Recently, I needed to integrate a database into a Rust application. Exploring the ecosystem, I encountered several options: from traditional SQL-based crates like Diesel and SQLx, to embedded key-value stores such as RocksDB, and more lightweight solutions like Sled. Each option offers different trade-offs in terms of performance, ease of use, scalability, and flexibility.

---

After testing and researching, I realized why Sled stands out for embedded, high-performance, and safe data storage in Rust applications. Below is a comparison of Sled against other common Rust database crates to help clarify the differences and why Sled could be the ideal choice depending on your project needs.

Sled guarantees crash-safety by using a lock-free, append-only log structure and supports atomic batch operations, making it ideal for concurrent embedded use

---

---

Code snippet

Here’s a simple example showing how easy it is to open a DB, and read/write data using Sled.

use sled::Db;

fn main() -> sled::Result<()> {
    let db: Db = sled::open("my_db")?;
    db.insert(b"key", b"value")?;
    let value = db.get(b"key")?;
    println!("Got: {:?}", value);
    Ok(())
}

Instead, a SQL example from the official documentation looks like this:

use sqlx::postgres::PgPoolOptions;
// use sqlx::mysql::MySqlPoolOptions;
// etc.

#[async_std::main] // Requires the `attributes` feature of `async-std`
// or #[tokio::main]
// or #[actix_web::main]
async fn main() -> Result<(), sqlx::Error> {
    // Create a connection pool
    //  for MySQL/MariaDB, use MySqlPoolOptions::new()
    //  for SQLite, use SqlitePoolOptions::new()
    //  etc.
    let pool = PgPoolOptions::new()
        .max_connections(5)
        .connect("postgres://postgres:password@localhost/test").await?;

    // Make a simple query to return the given parameter (use a question mark `?` instead of `$1` for MySQL/MariaDB)
    let row: (i64,) = sqlx::query_as("SELECT $1")
        .bind(150_i64)
        .fetch_one(&pool).await?;

    assert_eq!(row.0, 150);

    Ok(())
}

As you can see, it requires more configuration and async functions.

---

A direct comparison between sqlx and sled

---

When (and When Not) to Use Sled

When to use Sled:

• You need a fast, embedded key-value store for local storage in Rust applications.

• Your project requires crash-safe, concurrent data access without complex setup.

• You want a lightweight, minimal-dependency database that’s easy to integrate.

• Your application doesn’t require SQL queries or relational data modeling.

• You’re building embedded systems, desktop apps, or small services with local persistence.

When not to use Sled:

• You need full SQL support with complex queries, joins, and transactions.

• Your application requires a distributed or scalable multi-node database.

• You want to leverage existing relational database backends like Postgres or MySQL.

• You’re working in a no_std or bare-metal embedded environment.

• Your project demands extensive ORM features or schema migrations.

---

To summarize

Sled is a powerful option when you need reliable, lightweight, and high-performance local storage for Rust applications. It shines in scenarios where simplicity, speed, and safety matter more than SQL features or scalability. If your project doesn't need relational models or complex queries, sled might be the perfect tool for the job.

---

Link

You can find other info at the official GitHub page

💡 Other cool stuff?

☕ Was this helpful?

Treat me to a coffee on Ko-fi https://ko-fi.com/riccardoadami