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help / color / mirror / Atom feedFrom: Bruce Momjian <[email protected]>
To: Greg Sabino Mullane <[email protected]>
Cc: Dagfinn Ilmari Mannsåker <[email protected]>
Cc: pgsql-hackers <[email protected]>
Subject: Re: Changing the default random_page_cost value
Date: Mon, 14 Oct 2024 17:15:18 -0400
Message-ID: <[email protected]> (raw)
In-Reply-To: <CAKAnmmKxOq8i4JCfc6AzThuetLPenGaOQu25m0EeOhanaQdhLw@mail.gmail.com>
References: <CAKAnmmK_nSPYr53LobUwQD59a-8U9GEC3XGJ43oaTYJq5nAOkw@mail.gmail.com>
<[email protected]>
<CAKAnmmKxOq8i4JCfc6AzThuetLPenGaOQu25m0EeOhanaQdhLw@mail.gmail.com>
On Mon, Sep 30, 2024 at 10:05:29AM -0400, Greg Sabino Mullane wrote:
> On Fri, Sep 27, 2024 at 12:03 PM Dagfinn Ilmari Mannsåker <[email protected]>
> 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.
I am not a fan of this patch. I don't see why _removing_ the magnetic
part helps because you then have no logic for any 1.2 was chosen. I
would put the magnetic in a separate paragraph perhaps, and recommend
4.0 for it. Also, per-tablespace makes sense because of physical media
differences, but what purpose would per-database and per-role serve?
Also, per-tablespace is not a connection-activated item like the other
two.
--
Bruce Momjian <[email protected]> https://momjian.us
EDB https://enterprisedb.com
When a patient asks the doctor, "Am I going to die?", he means
"Am I going to die soon?"
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Subject: Re: Changing the default random_page_cost value
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