SULID: Snowflake-inspired Universally Unique Lexicographically Sortable Identifier

SULID is a unique ID generation algorithm that combines the benefits of ULID and Snowflake. It offers a highly efficient, reliable, and lexicographically sortable identifier, which ensures uniqueness across multiple data centers and machines, making it ideal for high-concurrency distributed environments.

Features

• High Concurrency Support: Efficiently generates unique IDs in high-concurrency environments.
• Time Ordered: It retains the time-ordered characteristic of ULID and supports both millisecond-level ordering and microsecond-level ordering.
• Distributed Uniqueness: Ensures unique IDs across distributed environments by incorporating data center and machine IDs.
• Readability: Produces shorter, human-readable identifiers.

Overview

SULID is based on the ULID (Universally Unique Lexicographically Sortable Identifier) format but incorporates additional bits for a data center ID and machine ID, similar to Snowflake. This design ensures uniqueness in distributed environments and maintains time-ordering characteristics, making it suitable for applications requiring both high concurrency and global uniqueness, such as microservice architectures, log tracking, and order generation.

ID Format

SULIDs have a unique structure comprising the following parts, adding up to a 128-bit identifier:

Millisecond-level Ordering

1. Timestamp: 42 bits, representing the epoch time in milliseconds.
2. Random Number: 76 bits of randomness to ensure uniqueness within the same millisecond.
3. Worker ID: 10 bits, the combination of data_center_id and machine_id.
   • Data Center ID: 5 bits, identifying the data center.
   • Machine ID: 5 bits, identifying the machine within the data center.

Here is a visual breakdown of the SULID format:

| 42-bit Timestamp | 76-bit Random Number | 10-bit Worker ID (5-bit Data Center ID | 5-bit Machine ID) |

Microsecond-level Ordering

1. Timestamp: 52 bits, representing the epoch time in milliseconds.
2. Random Number: 66 bits of randomness to ensure uniqueness within the same millisecond.
3. Worker ID: 10 bits, the combination of data_center_id and machine_id.
   • Data Center ID: 5 bits, identifying the data center.
   • Machine ID: 5 bits, identifying the machine within the data center.

Here is a visual breakdown of the SULID format:

| 52-bit Timestamp | 66-bit Random Number | 10-bit Worker ID (5-bit Data Center ID | 5-bit Machine ID) |

Installation

To use SULID, add the following dependencies to your Cargo.toml file:

[dependencies]
sulid = "0.7"

Usage

Here's how you can use the SulidGenerator in your project:

use sulid::{SulidGenerator, TimestampType};

fn main() {
    #[cfg(feature = "std")]
    {
        let generator = SulidGenerator::new1(1, 1, TimestampType::MS);

        for _ in 0..3 {
            let id = generator.generate();
            println!("SULID-MS: {}", id);
        }

        let generator = SulidGenerator::new2(1, TimestampType::US);

        for _ in 0..3 {
            let id = generator.generate();
            println!("SULID-US: {}", id);
        }
    }
    #[cfg(not(feature = "std"))]
    {
        let generator = SulidGenerator::new1(1, 1, TimestampType::MS);

        for i in 0..3 {
            let id = generator.generate(1736611200000, i);
            println!("SULID-MS: {}", id);
        }

        let generator = SulidGenerator::new2(1, TimestampType::US);

        for i in 0..3 {
            let id = generator.generate(1736611200000, i);
            println!("SULID-US: {}", id);
        }
    }
}

Example Output

Running the example code generates SULIDs such as:

SULID-V1: 01J75Y6K09Q0VD4D7HCF496K11
SULID-V1: 01J75Y6K09ZGD0ATFGNJ7TWZ11
SULID-V1: 01J75Y6K09DWG2RPNEXNYSRP11
SULID-V2: 01J75Y6K09FVT8QTQVYGSDJ401
SULID-V2: 01J75Y6K0A16WE3XQN92QPP701
SULID-V2: 01J75Y6K0AN12FBKX56YGZF301

Benefits

• High Concurrency Support: The algorithm is designed to generate IDs efficiently in environments with high concurrency, making it suitable for distributed systems.
• Time Ordered: SULID retains the time-ordering characteristic of ULID. This feature is beneficial for logging systems and event sourcing where chronological order is essential.
• Distributed Uniqueness: By incorporating data center and machine IDs similar to Snowflake's approach, SULID ensures IDs are unique across different machines and data centers.
• Readability: Compared to traditional UUIDs, SULID produces shorter and more human-readable identifiers, making them easier to work with in certain scenarios.
• Traceability: The time-ordered nature of SULID makes it easier to trace and debug events in distributed systems.

How It Works

SULID leverages both ULID and Snowflake's strengths:

• ULID: Provides lexicographically sortable identifiers based on a timestamp and randomness.
• Snowflake: Adds data center and machine IDs to ensure distributed uniqueness.

By combining these two approaches, SULID generates IDs that are globally unique, time-ordered, and suitable for high-concurrency distributed environments.

License

This project is licensed under the MIT License.