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 <877caxaxt6.fsf@wibble.ilmari.org>
In-Reply-To: <877caxaxt6.fsf@wibble.ilmari.org>
From: Greg Sabino Mullane <htamfids@gmail.com>
Date: Mon, 30 Sep 2024 10:05:29 -0400
Message-ID: <CAKAnmmKxOq8i4JCfc6AzThuetLPenGaOQu25m0EeOhanaQdhLw@mail.gmail.com>
Subject: Re: Changing the default random_page_cost value
To: =?UTF-8?Q?Dagfinn_Ilmari_Manns=C3=A5ker?= <ilmari@ilmari.org>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>
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On Fri, Sep 27, 2024 at 12:03=E2=80=AFPM Dagfinn Ilmari Manns=C3=A5ker <ilm=
ari@ilmari.org>
wrote:

> It might also be worth mentioning cloudy block storage (e.g. AWS' EBS),
> which is typically backed by SSDs, but has extra network latency.
>

That seems a little too in the weeds for me, but wording suggestions are
welcome. To get things moving forward, I made a doc patch which changes a
few things, namely:

* Mentions the distinction between ssd and hdd right up front.
* Moves the tablespace talk to the very end, as tablespace use is getting
rarer (again, thanks in part to ssds)
* Mentions the capability to set per-database and per-role since we mention
per-tablespace.
* Removes a lot of the talk of caches and justifications for the 4.0
setting. While those are interesting, I've been tuning this parameter for
many years and never really cared about the "90% cache rate". The proof is
in the pudding: rpc is the canonical "try it and see" parameter. Tweak.
Test. Repeat.

Cheers,
Greg

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<div dir=3D"ltr"><div dir=3D"ltr">On Fri, Sep 27, 2024 at 12:03=E2=80=AFPM =
Dagfinn Ilmari Manns=C3=A5ker &lt;<a href=3D"mailto:ilmari@ilmari.org">ilma=
ri@ilmari.org</a>&gt; wrote:<br></div><div class=3D"gmail_quote"><blockquot=
e class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px s=
olid rgb(204,204,204);padding-left:1ex">It might also be worth mentioning c=
loudy block storage (e.g. AWS&#39; EBS),<br>
which is typically backed by SSDs, but has extra network latency.<br></bloc=
kquote><div><br></div><div>That seems a little too in the weeds for me, but=
 wording suggestions are welcome. To get things moving forward, I made a do=
c patch which changes a few things, namely:</div><div><br></div><div>* Ment=
ions the distinction=C2=A0between ssd and hdd right up front.</div><div>* M=
oves the tablespace talk to the very end, as tablespace use is getting rare=
r (again, thanks in part to ssds)</div><div>* Mentions the capability to se=
t per-database and per-role since we mention per-tablespace.</div><div>* Re=
moves a lot of the talk of caches and justifications for the 4.0 setting. W=
hile those are interesting, I&#39;ve been tuning this parameter for many ye=
ars and never really cared about the &quot;90% cache rate&quot;. The proof=
=C2=A0is in the pudding: rpc is the canonical &quot;try it and see&quot; pa=
rameter. Tweak. Test. Repeat.</div><div><br></div><div>Cheers,</div><div>Gr=
eg</div><div><br></div></div></div>

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