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List:       postgresql-admin
Subject:    Re: Sanity check of shared_buffers value
From:       jacob ndinkwa <jndinkwa () gmail ! com>
Date:       2023-07-05 13:28:31
Message-ID: CAKFm-3BMEANY9Ftzkem5yyYq1qO3qmQ=DSJpkG+jSwAaOVby1g () mail ! gmail ! com
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You can use:

https://pgtune.leopard.in.ua/

for your cal.

Thanks,
-J

On Mon, Jul 3, 2023 at 4:46 PM Ron <ronljohnsonjr@gmail.com> wrote:

> Being AWS RDS is the kind of thing you need to mention.
>
> Anyway, plain old bash bc does it for you.  Explicitly:
> (24*1024^3)/1024/8
>
> Powershell, too:
> 24*[bigint]::pow(1024,3)/1024/8
>
> On 7/3/23 14:57, Wells Oliver wrote:
>
> Yeah. Unfortunately in AWS RDS the parameter group settings accept input
> only in stricter format, so shared_buffers requires an integer value in KiB.
>
> On Mon, Jul 3, 2023 at 12:56 PM Ron <ronljohnsonjr@gmail.com> wrote:
>
>> On 7/3/23 14:45, Wells Oliver wrote:
>>
>> Sorry, this is dumb, but I wanted to double check that I'm doing the
>> shared_buffers calc correctly given it's in 8kb blocks (block_size is set
>> to 8192).
>>
>> Want 24GB, which I think is 25165824 KiB so divided by 8 we get 3145728.
>>
>> Do I have this correct? Usually can test these but wanted to run it by
>> someone before having to restart the server.
>>
>> Is there some calc web service out there that idiots such as myself can
>> use for this?
>>
>>
>> https://www.postgresql.org/docs/15/runtime-config-resource.html
>>
>> "If this value is specified *without **units*, it is taken as blocks,"
>>
>> My interpretation of this (and what I do in my postgresql.conf file,
>> without error) is to use a unit name, as such:
>> shared_buffers = 24GB
>>
>> --
>> Born in Arizona, moved to Babylonia.
>>
>
>
> --
> Wells Oliver
> wells.oliver@gmail.com <wellsoliver@gmail.com>
>
>
> --
> Born in Arizona, moved to Babylonia.
>

[Attachment #3 (text/html)]

<div dir="ltr">You can use:<div><br></div><div><a \
href="https://pgtune.leopard.in.ua/">https://pgtune.leopard.in.ua/</a>    \
<br></div><div><br></div><div>for your \
cal.</div><div><br></div><div>Thanks,</div><div>-J</div></div><br><div \
class="gmail_quote"><div dir="ltr" class="gmail_attr">On Mon, Jul 3, 2023 at \
4:46 PM Ron &lt;<a \
href="mailto:ronljohnsonjr@gmail.com">ronljohnsonjr@gmail.com</a>&gt; \
wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px \
0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">  
    
  
  <div>
    Being AWS RDS is the kind of thing you need to mention.<br>
    <br>
    Anyway, plain old bash bc does it for you.   Explicitly:<br>
    (24*1024^3)/1024/8<br>
    <br>
    Powershell, too:<br>
    24*[bigint]::pow(1024,3)/1024/8<br>
    <br>
    <div>On 7/3/23 14:57, Wells Oliver wrote:<br>
    </div>
    <blockquote type="cite">
      
      <div dir="ltr">Yeah. Unfortunately in AWS RDS the parameter group
        settings accept input only in stricter format, so shared_buffers
        requires an  integer value in KiB.</div>
      <br>
      <div class="gmail_quote">
        <div dir="ltr" class="gmail_attr">On Mon, Jul 3, 2023 at
          12:56 PM Ron &lt;<a href="mailto:ronljohnsonjr@gmail.com" \
target="_blank">ronljohnsonjr@gmail.com</a>&gt;  wrote:<br>
        </div>
        <blockquote class="gmail_quote" style="margin:0px 0px 0px \
0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">  <div> On 7/3/23 \
14:45, Wells Oliver wrote:<br>  <blockquote type="cite">
              <div dir="ltr">Sorry, this is dumb, but I wanted to double
                check that I&#39;m doing the shared_buffers calc correctly
                given it&#39;s in 8kb blocks (block_size is set to 8192).
                <div><br>
                </div>
                <div>Want 24GB, which I think is  25165824 KiB so divided
                  by 8 we get  3145728.</div>
                <div><br>
                </div>
                <div>Do I have this correct? Usually can test these but
                  wanted to run it by someone before having to restart
                  the server.</div>
                <div><br>
                </div>
                <div>Is there some calc web service out there that
                  idiots such as myself can use for this?</div>
              </div>
            </blockquote>
            <br>
            <a href="https://www.postgresql.org/docs/15/runtime-config-resource.html" \
target="_blank">https://www.postgresql.org/docs/15/runtime-config-resource.html</a><br>
  <br>
            <span>&quot;If this value is specified <b>without </b><b>units</b>,
              it is taken as blocks,&quot;</span><br>
            <br>
            My interpretation of this (and what I do in my
            postgresql.conf file, without error) is to use a unit name,
            as such:<br>
            shared_buffers = 24GB<br>
            <br>
            <div>-- <br>
              Born in Arizona, moved to Babylonia.</div>
          </div>
        </blockquote>
      </div>
      <br clear="all">
      <div><br>
      </div>
      <span class="gmail_signature_prefix">-- </span><br>
      <div dir="ltr" class="gmail_signature">
        <div dir="ltr">
          <div>Wells Oliver<br>
            <a href="mailto:wellsoliver@gmail.com" \
target="_blank">wells.oliver@gmail.com</a></div>  </div>
      </div>
    </blockquote>
    <br>
    <div>-- <br>
      Born in Arizona, moved to Babylonia.</div>
  </div>

</blockquote></div>



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