Source code for UUIDv7 for PostgreSQL: https://gist.github.com/fabiolimace/515a0440e3e40efeb234e12644a6a346
create or replace function uuid7() returns uuid as $$
declare
begin
return uuid7(clock_timestamp());
end $$ language plpgsql;
create or replace function uuid7(p_timestamp timestamp with time zone) returns uuid as $$
declare
v_time double precision := null;
v_unix_t bigint := null;
v_rand_a bigint := null;
v_rand_b bigint := null;
v_unix_t_hex varchar := null;
v_rand_a_hex varchar := null;
v_rand_b_hex varchar := null;
c_milli double precision := 10^3; -- 1 000
c_micro double precision := 10^6; -- 1 000 000
c_scale double precision := 4.096; -- 4.0 * (1024 / 1000)
c_version bigint := x'0000000000007000'::bigint; -- RFC-9562 version: b'0111...'
c_variant bigint := x'8000000000000000'::bigint; -- RFC-9562 variant: b'10xx...'
begin
v_time := extract(epoch from p_timestamp);
v_unix_t := trunc(v_time * c_milli);
v_rand_a := trunc((v_time * c_micro - v_unix_t * c_milli) * c_scale);
v_rand_b := trunc(random() * 2^30)::bigint << 32 | trunc(random() * 2^32)::bigint;
v_unix_t_hex := lpad(to_hex(v_unix_t), 12, '0');
v_rand_a_hex := lpad(to_hex((v_rand_a | c_version)::bigint), 4, '0');
v_rand_b_hex := lpad(to_hex((v_rand_b | c_variant)::bigint), 16, '0');
return (v_unix_t_hex || v_rand_a_hex || v_rand_b_hex)::uuid;
end $$ language plpgsql;
Performance Testing
Testing for UUID generation
Setup
do
$$
declare
u uuid;
begin
for i in 1..10000000
loop
select gen_random_uuid() into u;
-- raise notice '%', u;
end loop;
end;
$$;
do
$$
declare
u uuid;
begin
for i in 1..10000000
loop
select uuid7() into u;
-- raise notice '%', u;
end loop;
end;
$$;
Test
mytest=# do
mytest-# $$
mytest$# declare
mytest$# u uuid;
mytest$# begin
mytest$# for i in 1..10000000
mytest$# loop
mytest$# select gen_random_uuid() into u;
mytest$# -- raise notice '%', u;
mytest$# end loop;
mytest$# end;
mytest$# $$;
DO
Time: 31743.056 ms (00:31.743)
-- each execution 0.031743056ms
mytest=# do
mytest-# $$
mytest$# declare
mytest$# u uuid;
mytest$# begin
mytest$# for i in 1..10000000
mytest$# loop
mytest$# select uuid7() into u;
mytest$# -- raise notice '%', u;
mytest$# end loop;
mytest$# end;
mytest$# $$;
DO
Time: 54132.676 ms (00:54.133)
-- each execution 0.054132676ms
Testing for UUID insertion
Setup
create table tbl_uuidv4
(u uuid primary key, c text);
insert into tbl_uuidv4
select gen_random_uuid(), 'additional data' from generate_series(1,10000000);
create table tbl_uuidv7
(u uuid primary key, c text);
insert into tbl_uuidv7
select uuid7(), 'additional data' from generate_series(1,10000000);
Test
mytest=# insert into tbl_uuidv4
mytest-# select gen_random_uuid(), 'additional data' from generate_series(1,10000000);
INSERT 0 10000000
Time: 60405.272 ms (01:00.405)
mytest=# insert into tbl_uuidv7
mytest-# select uuid7(), 'additional data' from generate_series(1,10000000);
INSERT 0 10000000
Time: 56902.619 ms (00:56.903)
mytest=# \dt+ tbl_uuid*
List of relations
Schema | Name | Type | Owner | Persistence | Access method | Size | Description
--------+------------+-------+----------+-------------+---------------+--------+-------------
public | tbl_uuidv4 | table | donghua | permanent | heap | 575 MB |
public | tbl_uuidv7 | table | donghua | permanent | heap | 575 MB |
(2 rows)
mytest=# \di+ tbl_uuid*
List of relations
Schema | Name | Type | Owner | Table | Persistence | Access method | Size | Description
--------+-----------------+-------+----------+------------+-------------+---------------+--------+-------------
public | tbl_uuidv4_pkey | index | donghua | tbl_uuidv4 | permanent | btree | 392 MB |
public | tbl_uuidv7_pkey | index | donghua | tbl_uuidv7 | permanent | btree | 301 MB |
(2 rows)
Testing how many buffers dirtied for UUID insertion
Setup
explain (analyze,buffers)
insert into tbl_uuidv4
select gen_random_uuid(), 'additional data' from generate_series(1,100);
explain (analyze,buffers)
insert into tbl_uuidv7
select uuid7(), 'additional data' from generate_series(1,100);
Test
mytest=# explain (analyze,buffers)
mytest-# insert into tbl_uuidv4
mytest-# select gen_random_uuid(), 'additional data' from generate_series(1,100);
QUERY PLAN
-------------------------------------------------------------------------------------------------------------------------------
Insert on tbl_uuidv4 (cost=0.00..2.25 rows=0 width=0) (actual time=40.337..40.338 rows=0 loops=1)
Buffers: shared hit=231 read=186 dirtied=106 written=1
-> Subquery Scan on "*SELECT*" (cost=0.00..2.25 rows=100 width=48) (actual time=0.038..1.379 rows=100 loops=1)
-> Function Scan on generate_series (cost=0.00..1.25 rows=100 width=48) (actual time=0.037..1.306 rows=100 loops=1)
Planning Time: 0.048 ms
Execution Time: 40.365 ms
(6 rows)
Time: 41.754 ms
mytest=# explain (analyze,buffers)
mytest-# insert into tbl_uuidv7
mytest-# select uuid7(), 'additional data' from generate_series(1,100);
QUERY PLAN
--------------------------------------------------------------------------------------------------------------------------------
Insert on tbl_uuidv7 (cost=0.00..27.00 rows=0 width=0) (actual time=1.204..1.205 rows=0 loops=1)
Buffers: shared hit=219 dirtied=1 written=1
-> Subquery Scan on "*SELECT*" (cost=0.00..27.00 rows=100 width=48) (actual time=0.077..0.614 rows=100 loops=1)
-> Function Scan on generate_series (cost=0.00..26.00 rows=100 width=48) (actual time=0.076..0.594 rows=100 loops=1)
Planning Time: 0.036 ms
Execution Time: 1.227 ms
(6 rows)
Time: 1.904 ms
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