Re: Shared_buffers

Here's one cook article on using pg_buffercache...

https://www.keithf4.com/a-large-database-does-not-mean-large-shared_buffers/

Regards,
Michael Vitale

> Justin Pryzby <mailto:pryzby(at)telsasoft(dot)com>
> Tuesday, March 12, 2019 4:11 PM
>
> I've tuned ~40 postgres instances, primarily using log_checkpoints and
> pg_stat_bgwriter, with custom RRD graphs. pg_buffercache does provide some
> valuable insights, and I know it's commonly suggested to check
> histogram of
> usagecounts, but I've never had any idea how to apply that to tune
> shared_buffers.
>
> Could you elaborate on what procedure you suggest ?
>
> Justin
> MichaelDBA <mailto:MichaelDBA(at)sqlexec(dot)com>
> Tuesday, March 12, 2019 4:03 PM
> Set shared_buffers more accurately by using pg_buffercache extension
> and the related queries during high load times.
>
> Regards,
> Michael Vitale
>
>
> Michael Lewis <mailto:mlewis(at)entrata(dot)com>
> Tuesday, March 12, 2019 3:23 PM
> On Tue, Mar 12, 2019 at 2:29 AM Laurenz Albe <laurenz(dot)albe(at)cybertec(dot)at
> <mailto:laurenz(dot)albe(at)cybertec(dot)at>> wrote:
>
> Daulat Ram wrote:
> > I want to know about the working and importance of
> shared_buffers in Postgresql?
> > is it similar to the oracle database buffer cache?
>
> Yes, exactly.
>
> The main difference is that PostgreSQL uses buffered I/O, while
> Oracle usually
> uses direct I/O.
>
> Usually you start with shared_buffers being the minimum of a
> quarter of the
> available RAM and 8 GB.
>
>
> Any good rule of thumb or write up about when shared buffers in excess
> of 8GBs makes sense (assuming system ram 64+ GBs perhaps)?