Subject: Re: Interpreting shared_buffers setting
To: pgsql-performance@lists.postgresql.org
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From: Thomas Markus <t.markus@proventis.net>
Organization: proventis GmbH
Message-ID: <746a1925-c653-d805-dd83-560198f91523@proventis.net>
Date: Tue, 29 Jan 2019 13:35:42 +0100
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Hi,

check for blocksize (8k) as factor.

8k*131072=1G

regards
Thomas

Am 29.01.19 um 13:32 schrieb Bob Jolliffe:
> Excuse me if this is a silly question.  I am trying to fiddle with
> shared_buffers setting on postgresql 10.6 on ubuntu 18.04 server.
>
> I have this at bottom of my config file:
> shared_buffers = 1GB
>
> Yet when I check the setting from pg_setting I see something quite different:
>
> postgres=# SELECT name, setting FROM pg_settings where name = 'shared_buffers';
>        name      | setting
> ----------------+---------
>   shared_buffers | 131072
>
> Is this a question of units?  It looks like 128M.  Note when I change
> the setting to 2GB in conf file I see 262144 from pg_setting.  I am
> now unsure what the actual shared_buffers allocation is.  I cant see
> anything in the docs which tells me how to interpret the integer.
>
> Any clarification welcome.
>
> Regards
> Bob
>