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From: Mark Kirkwood <mark.kirkwood@catalyst.net.nz>
To: Neto pr <netopr9@gmail.com>
Cc: Fabio Pardi <f.pardi@portavita.eu>
Cc: pgsql-performance@lists.postgresql.org
Subject: Re: Why HDD performance is better than SSD in this case
Date: Mon, 23 Jul 2018 12:07:16 +1200
Message-ID: <c8c36fe8-e1a8-694a-70db-72f32bcda781@catalyst.net.nz> (raw)
In-Reply-To: <CA+wPC0O7=vVWBCHFO__H72EnA+=uQVt6EMhyLhmhd8hy8CPYuw@mail.gmail.com>
References: <CA+wPC0PsWacZpNX2OfRSSauUg9iNa7tReJU0oTLnM7K8PFFt6A@mail.gmail.com>
	<01bbbc88-2a47-f078-ea40-ab2c1acafa1f@portavita.eu>
	<CA+wPC0M=e5ZXd1NF1nz6mYfmPgys89vB4A74GmxnnK+KpA4_XA@mail.gmail.com>
	<d29dfb84-bb9a-d7c7-74eb-e263eae07901@catalyst.net.nz>
	<CA+wPC0PzsKEV48D3ibFpaYUnjbKgeEBrN60W-O0Wh2WaT-ph1A@mail.gmail.com>
	<ce163be0-06f7-8cc6-f407-cee62235c561@catalyst.net.nz>
	<4ae07b23-912b-e3fb-8e9a-2959c2a64f19@catalyst.net.nz>
	<CA+wPC0O7=vVWBCHFO__H72EnA+=uQVt6EMhyLhmhd8hy8CPYuw@mail.gmail.com>

Hi Neto,

In a great piece of timing my new experimental SSD arrived (WD Black 500 
G 3D NAND MVME) [1]. Doing some runs of query 9:

- default config: 7 minutes

- work_mem=1G, max_parallel_workers_per_gather=4: 3-4 minutes


Increasing either of these much more got me OOM errors (16 G of ram). 
Anyway, enjoy your benchmarking!

Cheers
Mark

[1] Yeah - I know this is a 'do not use me in production' type of SSD. 
It is however fine for prototyping and DSS scenario run type use.

On 20/07/18 12:52, Neto pr wrote:
>
> Mark,
> This query 9 is very hard, see my results for other queries (attached
> - test with secondary index and without secondary index - only primary
> keys), the SSD always wins in performance.
> Only for this query that he was the loser, so I put this topic in the list.
>
> Today I will not be able to check your test information in more
> detail, but I will return with more information soon.
>
> Best Regards
> Neto
>
>
>
>
>





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