ULID (Universally Unique Lexicographically Sortable Identifier) is a type of identifier designed to be both globally unique and sortable in a lexicographically manner. Here's a description:
ULID, short for Universally Unique Lexicographically Sortable Identifier, is a type of identifier specifically engineered to offer both global uniqueness and lexicographical sorting capabilities. Each ULID consists of two primary components:
- Timestamp: The first 48 bits of a ULID represent a timestamp, measured in milliseconds since the Unix epoch (00:00:00 UTC on January 1, 1970). This timestamp component ensures that ULIDs can be sorted chronologically based on their generation time.
- Randomness: The remaining 80 bits of a ULID are dedicated to randomness, generated using a cryptographically secure pseudo-random number generator (CSPRNG). This randomness component guarantees the uniqueness of ULIDs and helps minimize the probability of collisions.
Key characteristics of ULID include:
- Global Uniqueness: ULIDs are designed to be globally unique, ensuring that the likelihood of generating identical ULIDs is extremely low, even in distributed systems or concurrent processes.
- Lexicographical Sortability: ULIDs are sortable in a lexicographical manner, meaning they can be arranged in ascending or descending order based on their byte representation. This sorting property is particularly useful for indexing and querying data efficiently.
- Compactness: ULIDs are relatively compact, comprising 128 bits in total. This makes them efficient for storage and transmission across different systems and platforms.
- Compatibility: ULIDs are compatible with various programming languages and environments, making them suitable for a wide range of applications, including databases, distributed systems, and unique identifier generation tasks.
In summary, ULID offers a robust solution for generating unique identifiers with embedded timestamps, facilitating chronological sorting while maintaining global uniqueness across distributed environments.