Awesome
Universally Unique Lexicographically Sortable Identifier
A PostgreSQL (pgcrypto) implementation of alizain/ulid based on OK Log's Go port.
Background
A GUID/UUID can be suboptimal for many use-cases because:
- It isn't the most character efficient way of encoding 128 bits
- UUID v1/v2 is impractical in many environments, as it requires access to a unique, stable MAC address
- UUID v3/v5 requires a unique seed and produces randomly distributed IDs, which can cause fragmentation in many data structures
- UUID v4 provides no other information than randomness which can cause fragmentation in many data structures
A ULID however:
- Is compatible with UUID/GUID's
- 1.21e+24 unique ULIDs per millisecond (1,208,925,819,614,629,174,706,176 to be exact)
- Lexicographically sortable
- Canonically encoded as a 26 character string, as opposed to the 36 character UUID
- Uses Crockford's base32 for better efficiency and readability (5 bits per character)
- Case insensitive
- No special characters (URL safe)
- Monotonic sort order (correctly detects and handles the same millisecond)
Usage
SELECT generate_ulid(); -- Output: 01D45VGTV648329YZFE7HYVGWC
Specification
Below is the current specification of ULID as implemented in this repository.
Components
Timestamp
- 48 bits
- UNIX-time in milliseconds
- Won't run out of space till the year 10895 AD
Entropy
- 80 bits
String Representation
01AN4Z07BY 79KA1307SR9X4MV3
|----------| |----------------|
Timestamp Entropy
10 chars 16 chars
48bits 80bits
base32 base32