What is a CUID

Resources  |  What is a CUID

CUID stands for "Collision-resistant Unique Identifier." It is designed to be a more robust alternative to other unique identifier systems like UUIDs (Universally Unique Identifiers). CUIDs aim to provide better performance, easier readability, and reduced likelihood of collisions (two identical identifiers being generated).

Key Features of CUID

  1. Collision Resistance:

    • CUIDs are specifically designed to minimize the probability of generating the same identifier in distributed systems or when generating many identifiers in a short period.

  2. Readability:

    • CUIDs are more human-readable compared to UUIDs. They include a timestamp and are shorter in length.

  3. Performance:

    • Generating CUIDs is generally faster compared to UUIDs. This can be beneficial in high-performance applications.

  4. Sequential Ordering:

    • CUIDs are designed to be roughly sequential, which can be advantageous for certain database indexing strategies.

Structure of a CUID

A typical CUID looks like this: c1df8fbf-7601-4f75-b7e8-43132e21acb9. It consists of several parts:

  1. Prefix: c - Denotes that this is a CUID.
  2. Timestamp: The current timestamp to ensure uniqueness over time.
  3. Counter: A counter to handle multiple identifiers being generated in a very short time.
  4. Fingerprint: A machine-specific value to avoid collisions across different machines.
  5. Random: Additional randomness to further reduce the risk of collisions.

Generating CUIDs in Different Languages

JavaScript

To generate a CUID in JavaScript, you can use the cuid library:

npm install cuid

const cuid = require('cuid');

const id = cuid();
console.log(id);  // Example output: c1df8fbf-7601-4f75-b7e8-43132e21acb9

Python

To generate a CUID in Python, you can use a similar approach by creating a function based on the CUID specifications. Here is a simple implementation:

import time
import os
import random
import hashlib

def cuid():
    timestamp = int(time.time() * 1000)
    counter = random.randint(0, 16777215)
    machine_fingerprint = hashlib.md5(os.uname().nodename.encode()).hexdigest()[:4]
    random_part = ''.join(random.choices('abcdefghijklmnopqrstuvwxyz0123456789', k=6))
    
    return f'c{timestamp:x}{counter:x}{machine_fingerprint}{random_part}'

print(cuid())  # Example output: c16f5b2d6d0000cc02c16eaa6

Use Cases for CUIDs

  1. Database Records: Ensuring unique keys in a distributed database.
  2. Session Identifiers: Generating unique session IDs for web applications.
  3. Transaction IDs: Ensuring unique transaction IDs in financial applications.
  4. Log Entries: Unique identifiers for log entries to make them easy to trace and manage.

Summary

CUIDs provide a robust, collision-resistant, and performant way to generate unique identifiers. They are particularly useful in distributed systems and high-performance applications where traditional UUIDs might fall short. With their easy readability and sequential nature, CUIDs are an excellent choice for many modern software applications.