A UUID (Universally Unique Identifier) is a 128-bit identifier standardized by RFC 4122. UUIDs are designed to be unique across all devices and time without requiring a central registration authority.
UUID v4 uses cryptographically secure random numbers to generate identifiers. With 122 bits of randomness, the total number of possible UUID v4 values is approximately 5.3 x 10^36, making collisions virtually impossible in practice. UUIDs are the de facto standard for distributed ID generation in modern software systems.
Database IDs
Use UUIDs as primary keys for database records
API Keys
Generate unique identifiers for API tokens and keys
Session Tokens
Create unique session identifiers for user tracking
Distributed Systems
Generate collision-free IDs across distributed nodes
What is a UUID?
A UUID (Universally Unique Identifier) is a 128-bit identifier that is guaranteed to be unique across all devices and time. UUIDs are standardized by RFC 4122 and are commonly used as database primary keys, API tokens, and session identifiers.
What is UUID v4?
UUID v4 is a randomly generated UUID. It uses 122 bits of random data (6 bits are reserved for version and variant information). The probability of generating a duplicate is astronomically low, making it suitable for most use cases.
Are UUIDs the same as GUIDs?
Yes, GUID (Globally Unique Identifier) is Microsoft's implementation of the UUID standard. They are functionally identical and follow the same format: 8-4-4-4-12 hexadecimal characters separated by hyphens.
How random are UUID v4 identifiers?
UUID v4 uses cryptographically secure random number generation (crypto.getRandomValues). With 122 random bits, there are approximately 5.3 x 10^36 possible UUIDs. You would need to generate 1 billion UUIDs per second for about 85 years to have a 50% chance of a collision.
Can I use UUIDs as database primary keys?
Yes, UUIDs are widely used as primary keys in databases. They allow distributed ID generation without coordination. However, they are larger than auto-increment integers (16 bytes vs 4-8 bytes) and can impact index performance in some databases.
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