Re: PostgreSQL Read IOPS limit per connection

Justin,
Thanks for the quick response, I'll check it out.

Happy holidays,
Haroldo Kerry

On Thu, Dec 27, 2018 at 2:55 PM Justin Pryzby <pryzby(at)telsasoft(dot)com> wrote:

> On Thu, Dec 27, 2018 at 02:44:55PM -0200, Haroldo Kerry wrote:
> > PostgreSQL 9.6.10 on x86_64-pc-linux-gnu (Debian 9.6.10-1.pgdg80+1),
>
> > Connected to SAN: Dell Compellent SC2020, with 7 x Samsung PM1633 SSDs
> >
> https://www.samsung.com/us/labs/pdfs/collateral/pm1633-prodoverview-2015.pdf
> ,
> > RAID10+RAID5 configuration, 8GB Cache, read-write battery backed cache
> > enabled, connected via dedicated iSCSI switches and dedicated Ethernet
> > ports, in link aggregation mode (2x1Gbps max bandwidth).
>
> > I’m trying to figure out if PostgreSQL (PG) has some inherent limit on
> IOPS
> > per connection.
>
> postgres uses one server backend per client.
>
> > We tried to increase effective_io_size from 1 to 30, to no effect on
> > multiple tests.
>
>
> https://www.postgresql.org/docs/current/runtime-config-resource.html#RUNTIME-CONFIG-RESOURCE-ASYNC-BEHAVIOR
> => "Currently, this setting only affects bitmap heap scans."
>
> > Is this some inherent limitation of PG or am I misunderstanding
> something?
>
> It is a hsitoric limitation, but nowadays there's parallel query, which
> uses
> 2ndary "backend worker" processes.
>
> It's supported in v9.6 but much more versatile in v10 and v11.
>
> Justin
>

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Haroldo Kerry

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