Crate rusty_ulid [−] [src]
ULID - Universally Unique Lexicographically Sortable Identifier
UUID can be suboptimal for many uses-cases because:
- It isn't the most character efficient way of encoding 128 bits of randomness
- 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
Instead, herein is proposed ULID:
01ARZ3NDEKTSV4RRFFQ69G5FAV
- 128-bit compatibility with UUID
- 1.21e+24 unique ULIDs per millisecond
- 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)
Specification
Below is the current specification of ULID as implemented in this crate.
01AN4Z07BY 79KA1307SR9X4MV3
|----------| |----------------|
Timestamp Randomness
48bits 80bits
Components
Timestamp
- 48 bit integer
- UNIX-time in milliseconds
- Won't run out of space till the year 10895 AD.
Randomness
- 80 bits
- Cryptographically secure source of randomness, if possible
Sorting
The left-most character must be sorted first, and the right-most character sorted last (lexical order). The default ASCII character set must be used. Within the same millisecond, sort order is not guaranteed
Canonical String Representation
ttttttttttrrrrrrrrrrrrrrrr
where
t is Timestamp (10 characters)
r is Randomness (16 characters)
Encoding
Crockford's Base32 is used as shown. This alphabet excludes the letters I, L, O, and U to avoid confusion and abuse.
0123456789ABCDEFGHJKMNPQRSTVWXYZ
Re-exports
pub use crockford::DecodingError; |
Modules
crockford |
Contains functions for encoding and decoding of crockford Base32 strings. |
Structs
Ulid |
The ULID data type. |
Functions
new_ulid_bytes |
Returns new ULID bytes. |
new_ulid_string |
Returns a new ULID string. |