Add support for more time precision per latest RFC spec.

META.json

@@ -1,15 +1,15 @@
 {
   "name": "pg_uuidv7",
   "abstract": "Create UUIDv7 values in Postgres",
-  "version": "1.2.0",
+  "version": "1.3.0",
   "maintainer": "fboulnois <fboulnois@users.noreply.github.com>",
   "license": "open_source",
   "provides": {
     "pg_uuidv7": {
       "abstract": "Create UUIDv7 values in Postgres",
-      "file": "pg_uuidv7--1.2.sql",
+      "file": "pg_uuidv7--1.3.sql",
       "docfile": "README.md",
-      "version": "1.2.0"
+      "version": "1.3.0"
     }
   },
   "resources": {

Makefile

@@ -1,6 +1,6 @@
 MODULES = pg_uuidv7
 EXTENSION = pg_uuidv7
-DATA = pg_uuidv7--1.2.sql
+DATA = pg_uuidv7--1.3.sql
 
 PG_CONFIG = pg_config
 PGXS := $(shell $(PG_CONFIG) --pgxs)

pg_uuidv7--1.3.sql

@@ -0,0 +1,20 @@
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use '''CREATE EXTENSION "pg_uuidv7"''' to load this file. \quit
+
+-- 48 bits for ms since unix epoch (rollover in 10899), 74 bits of randomness
+CREATE FUNCTION uuid_generate_v7(extra_ts_precision int = 0)
+RETURNS uuid
+AS 'MODULE_PATHNAME', 'uuid_generate_v7'
+VOLATILE STRICT LANGUAGE C PARALLEL SAFE;
+
+-- extract the timestamp from a v7 uuid
+CREATE FUNCTION uuid_v7_to_timestamptz(uuid)
+RETURNS timestamptz
+AS 'MODULE_PATHNAME', 'uuid_v7_to_timestamptz'
+VOLATILE STRICT LANGUAGE C PARALLEL SAFE;
+
+-- create a v7 uuid from a timestamp
+CREATE FUNCTION uuid_timestamptz_to_v7(timestamptz, zero bool = false)
+RETURNS uuid
+AS 'MODULE_PATHNAME', 'uuid_timestamptz_to_v7'
+VOLATILE STRICT LANGUAGE C PARALLEL SAFE;

pg_uuidv7.c

@@ -19,9 +19,13 @@ PG_FUNCTION_INFO_V1(uuid_generate_v7);
 Datum uuid_generate_v7(PG_FUNCTION_ARGS)
 {
 	pg_uuid_t *uuid = palloc(UUID_LEN);
+	uint8_t extra_ts_p = 0;
 	struct timespec ts;
 	uint64_t tms;
 
+	if (!PG_ARGISNULL(0))
+		extra_ts_p = PG_GETARG_INT32(0);
+
 	if (!pg_strong_random(uuid, UUID_LEN))
 		ereport(ERROR,
 				(errcode(ERRCODE_INTERNAL_ERROR),
@@ -39,6 +43,13 @@ Datum uuid_generate_v7(PG_FUNCTION_ARGS)
 	tms = pg_hton64(tms << 16);
 	memcpy(&uuid->data[0], &tms, 6);
 
+	if (extra_ts_p > 1 && extra_ts_p <= 12) {
+		tms = (((uint64_t)ts.tv_nsec << extra_ts_p) / 1000000)
+				& ((1 << extra_ts_p) - 1);
+		tms = pg_hton64(tms << 48);
+		memcpy(&uuid->data[6], &tms, 2);
+	}
+
 	/*
 	 * Set magic numbers for a "version 7" UUID, see
 	 * https://www.ietf.org/archive/id/draft-ietf-uuidrev-rfc4122bis-00.html#name-uuid-version-7

pg_uuidv7.control

@@ -1,4 +1,4 @@
 comment = 'pg_uuidv7: create UUIDv7 values in postgres'
-default_version = '1.2'
+default_version = '1.3'
 module_pathname = '$libdir/pg_uuidv7'
 relocatable = true