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Thread: Sanity check of shared_buffers value

Sanity check of shared_buffers value

From
Wells Oliver
Date:
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?

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Re: Sanity check of shared_buffers value

From
Ron
Date:
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.

Re: Sanity check of shared_buffers value

From
Wells Oliver
Date:
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.


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Re: Sanity check of shared_buffers value

From
Ron
Date:
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.


--

--
Born in Arizona, moved to Babylonia.

Re: Sanity check of shared_buffers value

From
jacob ndinkwa
Date:
You can use:


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.


--

--
Born in Arizona, moved to Babylonia.