Re: Will higher shared_buffers improve tpcb-like benchmarks?

Please remove me from this list Serv. I do not use this db anymore and
fills my alerts daily.

On Tue, Jan 29, 2019 at 06:39 Saurabh Nanda <saurabhnanda(at)gmail(dot)com> wrote:

> Hi,
>
> I'm going crazy trying to optimise my Postgres config for a production
> setting [1] Once I realised random changes weren't getting my anywhere, I
> finally purchased PostgreSQL 10 - Higher Performance [2] and understood the
> impact of shared_buffers.
>
> IIUC, shared_buffers won't have any significant impact in the following
> scenario, right?
>
> -- DB size = 30GB
> -- shared_buffers = 2GB
> -- workload = tpcb-like
>
> This is because the tpcb-like workload selects & updates random rows from
> the DB [3]. Therefore, with a 2GB shared buffer, there is only a 6-7%
> chance (did I get my probability correct?) that the required data will be
> in the shared_buffer. Did I understand this correctly?
>
> If nothing else becomes the bottleneck (eg. periodically writing dirty
> pages to disk), increasing the shared_buffers to 15GB+ should have a
> significant impact, for this DB-size and workload, right? (The system has
> 64 GB RAM)
>
> [1] Related thread at
> https://www.postgresql.org/message-id/flat/CAPz%3D2oGdmvirLNX5kys%2BuiY7LKzCP4sTiXXob39qq6eDkEuk2Q%40mail.gmail.com
> [2]
> https://www.packtpub.com/big-data-and-business-intelligence/postgresql-10-high-performance
> [3] https://www.postgresql.org/docs/11/pgbench.html#id-1.9.4.10.7.2
>
> -- Saurabh.
>
--
Ethical axioms are found and tested not very differently from the axioms of
science. Truth is what stands the the test if experience.