My problem with ULID is that it is only length-compatible with UUID, not format-compatible, so it cannot be added to the UUID specs as a new version to the IETF RFC. That is why I prefer UUIDv6 proposal, which could be handled in PostgreSQL and any other implementation with almost no changes to the code.
hauleth
jc00ke
Exactly. That was the most annoying part for me: having to convert from one format to another. I didn’t really need ULID anyway, but it was nice to get some experience with it.
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hauleth
By format I do not mean hexadecimal representation, but binary representation. Just to make it clear. String 46529a99-5727-4655-b1e9-58ebb8d90c6f is NOT UUID.
0
RodolfoSilva
Snowflake IDs, GitHub - pggalaviz/exnowflake: A decentralized, unique, time based ID generator. · GitHub .
Docs:
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cjbottaro
Can you explain how to do this? I just get…
** (ArgumentError) Invalid argument; Expected: <<clock_seq::14>>, <<node::48>>
(uuid 1.1.8) lib/uuid.ex:250: UUID.uuid1/3
Thanks.
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cjbottaro
I just ported the Cassandra::Uuid::Generator code from the official Cassandra Ruby gem:
https://github.com/datastax/ruby-driver/blob/master/lib/cassandra/uuid/generator.rb#L157
defmodule TimeUuid do
use Bitwise, only_operators: true
@gregorian_offset 122192928000000000
def new(date_time, jitter \\ nil) do
jitter = jitter || :rand.uniform(65536)
clock_id = :rand.uniform(65536)
node_id = generate_node_id()
usecs = DateTime.to_unix(date_time, :microsecond) + jitter
t = @gregorian_offset + usecs * 10
time_hi = t &&& 0x0fff000000000000
time_mid = t &&& 0x0000ffff00000000
time_low = t &&& 0x00000000ffffffff
version = 1
clock_id = clock_id &&& 0x3fff
node_id = node_id &&& 0xffffffffffff
variant = 0x8000
n = (time_low <<< 96) ||| (time_mid <<< 48) ||| (time_hi <<< 16)
n = n ||| (version <<< 76)
n = n ||| ((clock_id ||| variant) <<< 48)
n = n ||| node_id
<<n::integer-size(128)>>
|> UUID.binary_to_string!()
end
def generate_node_id do
:math.pow(2, 47)
|> trunc()
|> :rand.uniform()
|> Bitwise.bor(0x010000000000)
end
end
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