Date: Tue, 30 Jan 2024 07:28:28 +0000 (UTC)
From: Sergey Prokhorenko <sergeyprokhorenko@yahoo.com.au>
To: Jelte Fennema-Nio <postgres@jeltef.nl>,
	"Andrey M. Borodin" <x4mmm@yandex-team.ru>
Cc: pgsql-hackers mailing list <pgsql-hackers@postgresql.org>,
	Aleksander Alekseev <aleksander@timescale.com>,
	=?UTF-8?Q?Przemys=C5=82aw_Sztoch?= <przemyslaw@sztoch.pl>,
	Nikolay Samokhvalov <nik@postgres.ai>,
	"David G. Johnston" <david.g.johnston@gmail.com>,
	Nick Babadzhanian <pgnickb@gmail.com>,
	Mat Arye <mat@timescaledb.com>,
	Peter Eisentraut <peter.eisentraut@enterprisedb.com>,
	Tom Lane <tgl@sss.pgh.pa.us>, Daniel Gustafsson <daniel@yesql.se>,
	Matthias van de Meent <boekewurm+postgres@gmail.com>,
	Nikolay Samokhvalov <samokhvalov@gmail.com>,
	"Kyzer Davis (kydavis)" <kydavis@cisco.com>,
	Andres Freund <andres@anarazel.de>,
	"brad@peabody.io" <brad@peabody.io>, Kirk Wolak <wolakk@gmail.com>
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Subject: Re: UUID v7
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Andrey,

I think this phrase is outdated: "This function can optionally accept a tim=
estamp used instead of current time.This allows implementation of k-way sot=
able identifiers."
This phrase=C2=A0is wrong:=C2=A0"Both functions return a version 4 (random)=
 UUID."
For this phrase the reason is unclear=C2=A0and the phrase is=C2=A0most like=
ly incorrect:
if large batches of UUIDs are generated at the+=C2=A0 =C2=A0same time it's =
possible that some UUIDs will store a time that is slightly later+=C2=A0 =
=C2=A0than their actual generation time

Sergey Prokhorenko

sergeyprokhorenko@yahoo.com.au=20

    On Tuesday, 30 January 2024 at 09:55:04 am GMT+3, Andrey M. Borodin <x4=
mmm@yandex-team.ru> wrote: =20
=20
=20

> On 30 Jan 2024, at 01:38, Jelte Fennema-Nio <postgres@jeltef.nl> wrote:
>=20
> Yeah, I liked the feature to generate UUIDv7 based on timestamp too.
> But following the spec seems more important than a nice feature to me.

PFA v15. Changes: removed timestamp argument, incorporated Jelte=E2=80=99s =
documentation addons.

Thanks!


Best regards, Andrey Borodin.
 =20
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<html><head></head><body><div class=3D"ydpa13b8149yahoo-style-wrap" style=
=3D"font-family:Helvetica Neue, Helvetica, Arial, sans-serif;font-size:16px=
;"><div><div dir=3D"ltr" data-setdir=3D"false"><span><span style=3D"color: =
rgb(38, 40, 42); font-family: Helvetica Neue, Helvetica, Arial, sans-serif;=
">Andrey,</span></span><br></div><div dir=3D"ltr" data-setdir=3D"false"><sp=
an><span style=3D"color: rgb(38, 40, 42); font-family: Helvetica Neue, Helv=
etica, Arial, sans-serif;"><br></span></span></div><div dir=3D"ltr" data-se=
tdir=3D"false"><span><span style=3D"color: rgb(38, 40, 42); font-family: He=
lvetica Neue, Helvetica, Arial, sans-serif;"><span>I think this phrase is o=
utdated: "</span></span></span><span style=3D"color: rgb(38, 40, 42);">This=
 function can optionally accept a timestamp used instead of current time.</=
span></div><div dir=3D"ltr" data-setdir=3D"false"><span><span style=3D"colo=
r: rgb(38, 40, 42); font-family: Helvetica Neue, Helvetica, Arial, sans-ser=
if;"><div><div>This allows implementation of k-way sotable identifiers."</d=
iv></div><div><br></div><div dir=3D"ltr" data-setdir=3D"false"><span><span>=
This  <span><span style=3D"color: rgb(38, 40, 42); font-family: Helvetica N=
eue, Helvetica, Arial, sans-serif; font-size: 16px;">phrase&nbsp;</span></s=
pan>is wrong:&nbsp;</span></span>"<b>Both </b>functions return a version <b=
>4 (random)</b> UUID."</div><div dir=3D"ltr" data-setdir=3D"false"><br></di=
v><div dir=3D"ltr" data-setdir=3D"false"><span>For this phrase <span>the re=
ason is unclear</span>&nbsp;and the <span><span style=3D"color: rgb(38, 40,=
 42); font-family: Helvetica Neue, Helvetica, Arial, sans-serif; font-size:=
 16px;">phrase is&nbsp;</span></span>most likely incorrect:</span><br></div=
><div dir=3D"ltr" data-setdir=3D"false"><div><div>if large batches of UUIDs=
 are generated at the</div><div>+&nbsp; &nbsp;same time it's possible that =
some UUIDs will store a time that is slightly <b>later</b></div><div>+&nbsp=
; &nbsp;than their actual generation time</div></div><br></div></span></spa=
n></div><div><br></div><div class=3D"ydpa13b8149signature">Sergey Prokhoren=
ko<br><br>sergeyprokhorenko@yahoo.com.au</div></div>
        <div><br></div><div><br></div>
       =20
        </div><div id=3D"ydp715c861cyahoo_quoted_7393873104" class=3D"ydp71=
5c861cyahoo_quoted">
            <div style=3D"font-family:'Helvetica Neue', Helvetica, Arial, s=
ans-serif;font-size:13px;color:#26282a;">
               =20
                <div>
                    On Tuesday, 30 January 2024 at 09:55:04 am GMT+3, Andre=
y M. Borodin &lt;x4mmm@yandex-team.ru&gt; wrote:
                </div>
                <div><br></div>
                <div><br></div>
                <div><div dir=3D"ltr"><br clear=3D"none"><div class=3D"ydp7=
15c861cyqt2989934414" id=3D"ydp715c861cyqtfd84701"><br clear=3D"none">&gt; =
On 30 Jan 2024, at 01:38, Jelte Fennema-Nio &lt;<a shape=3D"rect" href=3D"m=
ailto:postgres@jeltef.nl" rel=3D"nofollow" target=3D"_blank">postgres@jelte=
f.nl</a>&gt; wrote:<br clear=3D"none">&gt; <br clear=3D"none">&gt; Yeah, I =
liked the feature to generate UUIDv7 based on timestamp too.<br clear=3D"no=
ne">&gt; But following the spec seems more important than a nice feature to=
 me.</div><br clear=3D"none"><br clear=3D"none">PFA v15. Changes: removed t=
imestamp argument, incorporated Jelte=E2=80=99s documentation addons.<br cl=
ear=3D"none"><br clear=3D"none">Thanks!<br clear=3D"none"><br clear=3D"none=
"><br clear=3D"none">Best regards, Andrey Borodin.<div class=3D"ydp715c861c=
yqt2989934414" id=3D"ydp715c861cyqtfd25866"><br clear=3D"none"></div></div>=
</div>
            </div>
        </div></body></html>
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