UUID in Rust — uuid Crate, v7 Support, and Database Integration

Rust’s uuid crate is the standard library for UUID generation, with over 70 million downloads. Version 1.x added UUID v7 support via Uuid::now_v7(), making the upgrade from v4 straightforward.

Adding the uuid Crate

# Cargo.toml
[dependencies]
uuid = { version = "1", features = ["v4", "v7", "serde"] }

Feature flags control what is compiled in:

Generating UUIDs

use uuid::Uuid;

// UUID v4 — random
let id_v4 = Uuid::new_v4();
println!("{}", id_v4); // e.g. "550e8400-e29b-41d4-a716-446655440000"

// UUID v7 — time-ordered
let id_v7 = Uuid::now_v7();
println!("{}", id_v7); // e.g. "018fbe3a-4c5d-7000-8abc-0123456789ab"

Uuid::now_v7() reads the system clock via std::time::SystemTime::now() and generates 74 random bits for the remaining fields. The timestamp uses Unix milliseconds in the high 48 bits, conforming to RFC 9562.

Diesel Integration (PostgreSQL)

Diesel maps Uuid from the uuid crate to PostgreSQL’s uuid column type:

[dependencies]
diesel = { version = "2", features = ["postgres", "uuid"] }
uuid = { version = "1", features = ["v7"] }

use diesel::prelude::*;
use uuid::Uuid;

#[derive(Insertable)]
#[diesel(table_name = orders)]
pub struct NewOrder {
    pub id: Uuid,
    pub customer_id: Uuid,
}

fn create_order(conn: &mut PgConnection, customer_id: Uuid) -> QueryResult<usize> {
    let new_order = NewOrder {
        id: Uuid::now_v7(),
        customer_id,
    };
    diesel::insert_into(orders::table)
        .values(&new_order)
        .execute(conn)
}

No schema migration needed when switching from v4 to v7 — the uuid column type in PostgreSQL stores both versions identically as 16 bytes.

SQLx Integration

SQLx also supports the Uuid type natively:

[dependencies]
sqlx = { version = "0.8", features = ["postgres", "uuid", "runtime-tokio"] }
uuid = { version = "1", features = ["v7"] }

let id = Uuid::now_v7();
sqlx::query!("INSERT INTO orders (id) VALUES ($1)", id)
    .execute(&pool)
    .await?;

SQLx encodes the Uuid as PostgreSQL’s native uuid type via the encode trait — no manual conversion required.

Serde Serialization

With the serde feature enabled, Uuid derives Serialize and Deserialize automatically, serializing to the standard hyphenated string format:

use serde::{Deserialize, Serialize};
use uuid::Uuid;

#[derive(Serialize, Deserialize)]
struct OrderResponse {
    id: Uuid,       // serializes as "018fbe3a-4c5d-7000-8abc-0123456789ab"
    total: f64,
}

For compact JSON or binary formats, the uuid crate also supports serializing as a 16-byte array via uuid::serde::compact.

Related Resources

• uuid crate on crates.io
• uuid crate documentation
• Diesel ORM documentation
• SQLx — async Rust SQL toolkit