There are many heated arguments software developers have amongst each other. So. Many. Arguments. Like feral cats, software developers will hiss, growl, or bare their teeth when in the midst of such an argument. One debate amongst them, developers not cats, is the difference between a UUID and a GUID. We spoke to some developers to understand the pros and cons of each so we at globalGlob(**/*) make the final conclusion and save them from themselves.
GUIDs (pronounced goo-ID) are generally used with Microsoft technologies, though it's not a requirement. UUIDs (pronounced ooo-ID or sometimes U.U.I.D.) are used everywhere else. A lot of people use the terms interchangeably which leads to confusion amongst developers and I.T. workers, but they have distinct use cases.
| UUID | GUID | |
|---|---|---|
| Name | Universally Unique Identifier | Globally Unique Identifier |
| Size | 128 bits | 16 Bytes |
| Total Possible Numbers | 2^128 | 340,282,366,899,999,981,604,444,818,997,342,371,840 |
| Collision Probability | Virtually Impossible | Ain't Gonna Happen |
| Display Format | 8-4-4-4-12 hexadecimal characters | 32 Characters. 0-9, A-F, grouped with hyphens |
You can clearly see the differences in the chart. The amount of space used, performance characteristics, even the display encodings can be wildly different. You've obviously already come to your own conclusions about which is better, but the goal of this article is to help the software development community by choosing one over the other.
The logic is clear that GUIDs are global, and UUIDs are universal. Since the universe if bigger than the globe, UUIDs are better and should be used instead of GUIDs. We're sorry if this means you have to change your code, but it's important for everyone to use the right tool for the job.