# ulid.lua

**Repository Path**: mirrors_Tieske/ulid.lua

## Basic Information

- **Project Name**: ulid.lua
- **Description**: Universally Unique Lexicographically Sortable Identifier for Lua
- **Primary Language**: Unknown
- **License**: MIT
- **Default Branch**: master
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 0
- **Created**: 2020-08-18
- **Last Updated**: 2025-12-27

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README

# Universally Unique Lexicographically Sortable Identifier for Lua

Based on the [implementation by alizain](https://github.com/alizain/ulid)

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:

- 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)

## Lua

### Installation

```
luarocks install ulid
```

### Usage

```lua
local ulid_mod = require("ulid")

print(ulid_mod.ulid())  -- 01ARZ3NDEKTSV4RRFFQ69G5FAV
```

## Specification

Below is the current specification of ULID as implemented in this repository.

*Note: the binary format has not been implemented.*

```
 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
- Please make sure to use 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

### Encoding

Crockford's Base32 is used as shown. This alphabet excludes the letters I, L, O, and U to avoid confusion and abuse.

```
0123456789ABCDEFGHJKMNPQRSTVWXYZ
```

### String Representation

```
ttttttttttrrrrrrrrrrrrrrrr

where
t is Timestamp
r is Randomness
```

## Test Suite

Tests can be run from the repo using `busted`

```
busted
```