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Subject: Re: About asynchronous I/O
From: bertrand HARTWIG <hartwig.bertrand@gmail.com>
In-Reply-To: <1116567729.67464.1782219863407@connect.xfinity.com>
Date: Tue, 23 Jun 2026 15:35:04 +0200
Cc: Ron Johnson <ronljohnsonjr@gmail.com>,
 Pgsql-admin <pgsql-admin@lists.postgresql.org>
Message-Id: <B9BDF1A5-EDD2-4648-8624-C480375FF5D8@gmail.com>
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To: JOHN WIENCEK <jwiencek3@comcast.net>
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Linux Io_uring is used by PostgreSQL only with aio_read() =E2=80=A6


> Le 23 juin 2026 =C3=A0 15:04, JOHN WIENCEK <jwiencek3@comcast.net> a =
=C3=A9crit :
>=20
> Can your application assume the risk of lost transactions in the event =
of a database crash?
> ASYNC/IO is not a good solution for all applications.
>=20
>=20
> Regards
>=20
> John
>> On 06/23/2026 7:19 AM CDT bertrand HARTWIG =
<hartwig.bertrand@gmail.com> wrote:
>> =20
>> =20
>> Very usefull on SSD AND nvme ! (low latency on IOPs). But the higher =
the disk latency, the greater the gains you will notice.
>> =20
>> On SSD i observed 200%
>>=20
>>> Le 23 juin 2026 =C3=A0 14:02, Ron Johnson <ronljohnsonjr@gmail.com> =
a =C3=A9crit :
>>> On Tue, Jun 23, 2026 at 7:26=E2=80=AFAM bertrand HARTWIG =
<hartwig.bertrand@gmail.com <mailto:hartwig.bertrand@gmail.com>> wrote:
>>> Hello,
>>>=20
>>> The size of the database is clearly not important.
>>>=20
>>> What matters are queries that are not already cached and that =
perform I/O.
>>>=20
>>> With async I/O, you can see I/O performance improvements of up to =
200%=E2=80=93300%. The higher the disk latency, the greater the gains =
you will notice.
>>>=20
>>> =20
>>> So, not so useful on SSD/NVMe?
>>> =20
>>> Regards,
>>>=20
>>> Bertrand
>>>=20
>>>=20
>>>> Le 23 juin 2026 =C3=A0 09:55, ek ek <livadidrive@gmail.com =
<mailto:livadidrive@gmail.com>> a =C3=A9crit :
>>>>=20
>>>> Hello everyone,
>>>> Are any of you running PostgreSQL 18 on production environments =
sized between 1 to 3TB? Does the 'asynchronous I/O (AIO) subsystem' =
deliver a significant performance increase? Also, has anyone had the =
opportunity to benchmark it against v17?
>>>=20
>>> =20
>>> =20
>>> --
>>> Death to <Redacted>, and butter sauce.
>>> Don't boil me, I'm still alive.
>>> <Redacted> lobster!


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	charset=utf-8

<html aria-label=3D"message body"><head><meta http-equiv=3D"content-type" =
content=3D"text/html; charset=3Dutf-8"></head><body =
style=3D"overflow-wrap: break-word; -webkit-nbsp-mode: space; =
line-break: after-white-space;">Linux Io_uring is used by PostgreSQL =
only with aio_read() =E2=80=A6<div><br></div><div><br><div><div><blockquot=
e type=3D"cite"><div>Le 23 juin 2026 =C3=A0 15:04, JOHN WIENCEK =
&lt;jwiencek3@comcast.net&gt; a =C3=A9crit :</div><br =
class=3D"Apple-interchange-newline"><div>

 =20
  <meta charset=3D"UTF-8">=20
=20
 <div>
  <div style=3D"font-size: 12pt; font-family: =
helvetica,arial,sans-serif; color: #333333;">
   <span style=3D"font-family: helvetica; font-size: 12pt;">Can your =
application assume the risk of lost transactions in the event of a =
database crash?<br></span>=20
   <div>
    ASYNC/IO is not a good solution for all applications.
   </div> <span style=3D"font-family: helvetica; font-size: =
12pt;"><br><br></span>=20
   <div>
    Regards
   </div> <span style=3D"font-family: helvetica; font-size: =
12pt;"><br></span>=20
   <div>
    John
   </div>=20
  </div>=20
  <blockquote type=3D"cite">=20
   <div>
    On 06/23/2026 7:19 AM CDT bertrand HARTWIG =
&lt;hartwig.bertrand@gmail.com&gt; wrote:
   </div>=20
   <div>
    &nbsp;
   </div>=20
   <div>
    &nbsp;
   </div> Very usefull on SSD AND nvme ! (low latency on IOPs). But the =
higher the disk latency, the greater the gains you will notice.=20
   <div>
    &nbsp;
   </div>=20
   <div>
    On SSD i observed 200%
    <br id=3D"lineBreakAtBeginningOfMessage">=20
    <div>
     <br>=20
     <blockquote type=3D"cite">=20
      <div>
       Le 23 juin 2026 =C3=A0 14:02, Ron Johnson =
&lt;ronljohnsonjr@gmail.com&gt; a =C3=A9crit :
      </div>=20
      <div>=20
       <div dir=3D"ltr">=20
        <div dir=3D"ltr">
         <span style=3D"background-color: transparent;">On Tue, Jun 23, =
2026 at 7:26=E2=80=AFAM bertrand HARTWIG &lt;<a =
href=3D"mailto:hartwig.bertrand@gmail.com">hartwig.bertrand@gmail.com</a>&=
gt; wrote:</span>
        </div>=20
        <div class=3D"gmail_quote gmail_quote_container">=20
         <blockquote>=20
          <div><p>Hello,</p><p>The size of the database is clearly not =
important.</p><p>What matters are queries that are not already cached =
and that perform I/O.</p><p>With async I/O, you can see I/O performance =
improvements of up to 200%=E2=80=93300%. The higher the disk latency, =
the greater the gains you will notice.</p>=20
          </div>=20
         </blockquote>=20
         <div>
          &nbsp;
         </div>=20
         <div>
          So, not so useful on SSD/NVMe?
         </div>=20
         <div>
          &nbsp;
         </div>=20
         <blockquote>=20
          <div><p>Regards,</p><p>Bertrand</p>=20
           <div>=20
            <div>
             <br>=20
             <blockquote type=3D"cite">=20
              <div>
               Le 23 juin 2026 =C3=A0 09:55, ek ek &lt;<a =
href=3D"mailto:livadidrive@gmail.com" target=3D"_blank" =
rel=3D"noopener">livadidrive@gmail.com</a>&gt; a =C3=A9crit :
              </div>=20
              <br>=20
              <div>=20
               <div dir=3D"auto">=20
                <div dir=3D"auto">
                 Hello everyone,
                </div>=20
                <div dir=3D"auto">
                 Are any of you running PostgreSQL 18 on production =
environments sized between 1 to 3TB? Does the 'asynchronous I/O (AIO) =
subsystem' deliver a significant performance increase? Also, has anyone =
had the opportunity to benchmark it against v17?
                </div>=20
               </div>=20
              </div>=20
             </blockquote>=20
            </div>=20
           </div>=20
          </div>=20
         </blockquote>=20
        </div>=20
        <div>
         &nbsp;
        </div>=20
        <div>
         &nbsp;
        </div> <span class=3D"gmail_signature_prefix">-- </span>
        <br>=20
        <div class=3D"gmail_signature" dir=3D"ltr">=20
         <div dir=3D"ltr">
          Death to &lt;Redacted&gt;, and butter sauce.=20
          <div>
           Don't boil me, I'm still alive.
           <br>=20
           <div>=20
            <div>
             &lt;Redacted&gt; lobster!
            </div>=20
           </div>=20
          </div>=20
         </div>=20
        </div>=20
       </div>=20
      </div>=20
     </blockquote>=20
    </div>=20
   </div>=20
  </blockquote>
 </div>
</div></blockquote></div><br></div></div></body></html>=

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