The False Choice Between UUIDs and Numeric IDs: Use Both!

In the world of database design, few decisions are as fundamental as how you'll identify your records. Should you use auto-incrementing numeric IDs? Or should you opt for the seemingly random, globally unique identifiers known as UUIDs? This debate has raged for years among developers and database administrators.

But here's the thing: this isn't actually an either/or situation. In fact, the most robust applications use both types of identifiers strategically. Let me show you why.

Understanding Numeric IDs: The Database's Best Friend

Sequential numeric IDs have been the backbone of relational databases since their inception. They're simple, compact, and incredibly efficient for what databases do best: joining tables and organizing data.

Advantages of Numeric IDs

1. Database Performance: Numeric IDs are typically stored as integers, which databases can process extremely efficiently. Join operations across tables with integer keys are lightning fast.

2. Space Efficiency: Integer IDs typically require just 4 bytes of storage compared to UUIDs which need 16 bytes. This might seem trivial until you're dealing with billions of records.

3. Human Readability: It's much easier to remember and communicate "user 1842" than "user 550e8400-e29b-41d4-a716-446655440000".

4. Natural Ordering: Sequential IDs maintain a chronological order that can be useful for understanding when records were created.

5. Auto-Incrementing: Most databases support automatically incrementing these IDs, making it easy to keep track of rows, sort tables, and avoid ID collisions.

Understanding UUIDs: The External-Facing Champion

UUID stands for Universally Unique Identifier. These 128-bit values are designed to be globally unique without requiring a central authority to issue them. The complete inner workings of UUIDs are beyond the scope of this article, but suffice to say that they are usually derived from timestamps, network addresses, hashing algorithms like MD5 or SHA-1, and other sources of entropy. The probability of collision is low enough to be effectively zero.

Think of it this way: If you generated 1 trillion UUIDs every second for a year, the probability of finding a collision would still be astronomically small - about 0.00000006%. You'd have better odds of winning the lottery multiple times in a row.

In practical terms, UUID collisions are so improbable that most systems treat them as impossible, and engineers worry about other failure modes long before considering UUID collisions as a realistic concern.

Advantages of UUIDs

1. Security: UUIDs don't reveal information about your database size or growth rate, unlike sequential IDs which can expose this information.

2. Distributed Systems: UUIDs can be generated independently across multiple services without coordination, making them perfect for microservices architectures.

3. Data Portability: When merging databases or importing/exporting data, UUIDs prevent ID collisions that would occur with numeric IDs.

4. Privacy: Using UUIDs in URLs and public-facing interfaces prevents enumeration attacks where someone might try to access resources by incrementing IDs sequentially.

The Hybrid Approach: Getting the Best of Both Worlds

Instead of choosing one system exclusively, modern applications benefit from using both types of identifiers with clearly defined purposes:

Internal IDs (Numeric)

Use auto-incrementing numeric IDs for:

• Primary keys within your database

• Foreign key relationships

• Internal operations and queries

• Database maintenance and optimization

External IDs (UUIDs)

Use UUIDs for:

• Public-facing APIs

• URLs and resource identifiers

• Cross-system integrations

• Distributed data generation

Implementation of a Dual ID Strategy

Here are some practical ways to implement this dual-ID approach:

Table Structure:

CREATE TABLE users (
  id INT PRIMARY KEY AUTO_INCREMENT,
  uuid CHAR(36) UNIQUE NOT NULL,
  -- other fields
);

1. UUID Generation: Generate UUIDs upon record creation, either through application code or database functions.

2. API Design: Your internal services can use numeric IDs for efficiency, while your external APIs exclusively use UUIDs.

3. URL Routing: Map incoming UUID-based requests to internal numeric IDs for processing.

Wait, Hold Up, I have Questions

"This feels like unnecessary complexity."

The minimal overhead of maintaining two ID fields is far outweighed by the benefits in security, performance, and system design flexibility.

"Won't this slow down my database?"

While there is a small storage overhead, proper indexing ensures that lookups by UUID remain efficient. Meanwhile, your internal operations benefit from the speed of integer IDs.

"What about existing systems?"

For legacy systems, you can introduce UUIDs gradually, starting with new tables or by adding UUID columns to existing tables during maintenance windows.

GibsonAI’s Approach to Numeric IDs Vs UUIDs

Given that this article advocating a hybrid approach is here on our blog, you can probably guess our position on the issue. GibsonAI creates and deploys production-ready databases, so we insist on following best practices. Therefore, all of our tables and schemas include both numeric IDs for internal joins and lookups, and UUIDs for external-facing purposes. Of course, everything is properly indexed and referenced. Bet.

Embrace the Dual-ID Approach

The choice between numeric IDs and UUIDs isn't a zero-sum game. By using numeric IDs internally for database efficiency while exposing UUIDs externally for security and system design benefits, you get the advantages of both approaches with minimal drawbacks.

This hybrid approach represents the current best practice in modern application design. It acknowledges the reality that different contexts have different requirements. Internal database operations need the speed and efficiency of numeric IDs, while external interfaces benefit from the security and flexibility of UUIDs.

So, the next time you're designing a database schema, remember: you don't have to choose. Use both types of identifiers strategically, and your application will be better for it.