buid:   universally unique lexicographically sortable identifiers
1 Spec
2 Reference
buid/  c
buid-bytes/  c
make-buid-factory
buid
buid-time
buid-posix-time
buid-randomness
buid->bytes
bytes->buid
8.2

buid: universally unique lexicographically sortable identifiers

Bogdan Popa <bogdan@defn.io>

 (require buid) package: buid

This package provides an implementation of flake ids that are lexicographically-sortable and highly unlikely to collide in a distributed system.

BUIDs can (and are meant to!) be safely stored inside a PostgreSQL UUID field.

1 Spec

A BUID is made up of a 40 bit time component and an 88 bit randomness component. The time component represents the current number of centiseconds since the UNIX timestamp 1586026830000.

BUIDs are represented as 22 character strings where the first 7 characters represent the 0-padded time component encoded in base 62 and the remaining 15 characters represent the 0-padded randomness component encoded in base 62.

The randomness component must have its most significant bit initially set to 0 and all ids generated within the same centisecond must increase monotonically.

In binary, BUIDs are represented as 16 bytes, encoded in network order.

2 Reference

value

buid/c : string?

Represents a BUID string.

Represents the binary representation of a BUID.

procedure

(make-buid-factory)  (-> (and/c buid/c immutable?))

Returns a function that can be used to generate BUIDs. Any BUIDs generated within the same centisecond by the resulting function will increase monotonically.

The generator functions are thread-safe.

procedure

(buid)  (-> (and/c buid/c immutable?))

Generates an BUID.

> (require buid)
> (for ([_ (in-range 10)]) (displayln (buid)))

04QzOcf00MlWHRf6LC4Mo0

04QzOcf00MlWHRf6LC4Mo1

04QzOcf00MlWHRf6LC4Mo2

04QzOcf00MlWHRf6LC4Mo3

04QzOcf00MlWHRf6LC4Mo4

04QzOcf00MlWHRf6LC4Mo5

04QzOcf00MlWHRf6LC4Mo6

04QzOcf00MlWHRf6LC4Mo7

04QzOcf00MlWHRf6LC4Mo8

04QzOcf00MlWHRf6LC4Mo9

procedure

(buid-time s)  exact-nonnegative-integer?

  s : buid/c
Returns the time component of the BUID s.

Returns the time component of the BUID s, adjusted to a POSIX timestamp in milliseconds.

Returns the random component of the BUID s.

procedure

(buid->bytes u)  buid-bytes/c

  u : buid/c
Returns the binary representation of the BUID u.

procedure

(bytes->buid bs)  buid/c

  bs : buid-bytes/c
Converts bs to a BUID. Raises an error if the result is not a valid BUID.