Re: Interpreting shared_buffers setting

Bob Jolliffe <bobjolliffe(at)gmail(dot)com> writes:

> 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

Why not use the show command which is good about output in human
terms...

psql (11.1 (Ubuntu 11.1-1.pgdg16.04+1))
Type "help" for help.

meta_a:postgres# select name, setting from pg_settings where name = 'shared_buffers');
ERROR: syntax error at or near ")"
LINE 1: ...me, setting from pg_settings where name = 'shared_buffers');
^
meta_a:postgres#

>
> 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
>
>

--
Jerry Sievers
Postgres DBA/Development Consulting
e: postgres(dot)consulting(at)comcast(dot)net