UUID Note


1.github - uuidv7: A JavaScript implementation of UUID version 7

https://github.com/LiosK/uuidv7
https://unpkg.com/uuidv7@1.0.2/dist/index.js

2.sql function: Implementing V7 UUID in Postgres - How to implement v7 UUID in postgres with using SQL

https://priver.dev/blog/postgres/implementing-v7-uuid-in-postgres/#:~:text=We%20use%20clock_timestamp%20to%20obtain%20the%20current%20time%2C,millisecond%20timestamp%20to%20a%20byte%20sequence%20using%20int8send.

CREATE EXTENSION IF NOT EXISTS "uuid-ossp";

create or replace function uuid_generate_v7()
returns uuid
as $$
select encode(
    set_bit(
      set_bit(
        overlay(uuid_send(gen_random_uuid())
                placing substring(int8send(floor(extract(epoch from clock_timestamp()) * 1000)::bigint) from 3)
                from 1 for 6
        ),
        52, 1
      ),
      53, 1
    ),
    'hex')::uuid;
$$
language SQL
volatile;


3.Extract Timestamp from UUID v7 using Javascript

https://park.is/blog_posts/20240803_extracting_timestamp_from_uuid_v7/

// extract Unix timestamp from a UUID v7 value without an external library

在没有外部库的情况下从 UUID v7 值中提取 Unix 时间戳
function extractTimestampFromUUIDv7(uuid: string): Date {
  // split the UUID into its components
  const parts = uuid.split("-");

  // the second part of the UUID contains the high bits of the timestamp (48 bits in total)
  const highBitsHex = parts[0] + parts[1].slice(0, 4);

  // convert the high bits from hex to decimal
  // the UUID v7 timestamp is the number of milliseconds since Unix epoch (January 1, 1970)
  const timestampInMilliseconds = parseInt(highBitsHex, 16);

  // convert the timestamp to a Date object
  const date = new Date(timestampInMilliseconds);

  return date;
}

// sample usage:
const uuid = "01911825-7f8f-74c9-85bc-55b034e2af75";
const timestamp = extractTimestampFromUUIDv7(uuid);

// check output
console.log(timestamp);
// prints "Sat Aug 03 2024 07:09:56 GMT-0500 (Central Daylight Time)"