From 8a187711baf7bc38fb6cd5e441a7e41b33695388 Mon Sep 17 00:00:00 2001
From: cc <xpsion@qq.com>
Date: Mon, 3 Mar 2025 15:21:30 +0800
Subject: [PATCH] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=20UUID.md?=
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+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)"
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