Re: Why HDD performance is better than SSD in this case

From: Mark Kirkwood
Subject: Re: Why HDD performance is better than SSD in this case
Date: ,
Msg-id: 4fc347b1-a7f9-c0cf-58e6-99f0c37028b2@catalyst.net.nz
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In response to: Why HDD performance is better than SSD in this case  (Neto pr)
List: pgsql-performance

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Why HDD performance is better than SSD in this case  (Neto pr, )
 Re: Why HDD performance is better than SSD in this case  (Benjamin Scherrey, )
  Re: Why HDD performance is better than SSD in this case  (winston cheung, )
 Re: Why HDD performance is better than SSD in this case  (Mark Kirkwood, )
 Re: Why HDD performance is better than SSD in this case  (Robert Zenz, )
 Re: Why HDD performance is better than SSD in this case  (Fabio Pardi, )
  Re: Why HDD performance is better than SSD in this case  (Neto pr, )
   Re: Why HDD performance is better than SSD in this case  (Neto pr, )
    Re: Why HDD performance is better than SSD in this case  (Nicolas Charles, )
     Re: Why HDD performance is better than SSD in this case  (Robert Zenz, )
      Re: Why HDD performance is better than SSD in this case  (Nicolas Charles, )
     Re: Why HDD performance is better than SSD in this case  (Neto pr, )
      Re: Why HDD performance is better than SSD in this case  (Nicolas Charles, )
     Re: Why HDD performance is better than SSD in this case  (Mark Kirkwood, )
    Re: Why HDD performance is better than SSD in this case  (Fabio Pardi, )
     Re: Why HDD performance is better than SSD in this case  (Neto pr, )
      Re: Why HDD performance is better than SSD in this case  (Fabio Pardi, )
       Re: Why HDD performance is better than SSD in this case  (Neto pr, )
        Re: Why HDD performance is better than SSD in this case  (Fabio Pardi, )
   Re: Why HDD performance is better than SSD in this case  (Mark Kirkwood, )
    Re: Why HDD performance is better than SSD in this case  (Neto pr, )
     Re: Why HDD performance is better than SSD in this case  (Neto pr, )
      Re: Why HDD performance is better than SSD in this case  (Nicolas Charles, )
      Re: Why HDD performance is better than SSD in this case  (Imre Samu, )
     Re: Why HDD performance is better than SSD in this case  (Mark Kirkwood, )
     Re: Why HDD performance is better than SSD in this case  (Mark Kirkwood, )
      Re: Why HDD performance is better than SSD in this case  (Mark Kirkwood, )
       Re: Why HDD performance is better than SSD in this case  (Neto pr, )
        Re: Why HDD performance is better than SSD in this case  (Mark Kirkwood, )
       Re: Why HDD performance is better than SSD in this case  (Mark Kirkwood, )
 Re: Why HDD performance is better than SSD in this case  (Jeff Janes, )
 Re: Why HDD performance is better than SSD in this case  (George Neuner, )

Can you post make and model of the SSD concerned? In general the cheaper 
consumer grade ones cannot do sustained read/writes at anything like 
their quoted max values.

regards

Mark


On 17/07/18 17:00, Neto pr wrote:
> Dear,
> Some of you can help me understand this.
>
> This query plan is executed in the query below (query 9 of TPC-H
> Benchmark, with scale 40, database with approximately 40 gb).
>
> The experiment consisted of running the query on a HDD (Raid zero).
> Then the same query is executed on an SSD (Raid Zero).
>
> Why did the HDD (7200 rpm)  perform better?
> HDD - TIME 9 MINUTES
> SSD - TIME 15 MINUTES
>
> As far as I know, the SSD has a reading that is 300 times faster than SSD.
>
> --- Execution  Plans---
> ssd 40g
> https://explain.depesz.com/s/rHkh
>
> hdd 40g
> https://explain.depesz.com/s/l4sq
>
> Query ------------------------------------
>
> select
>      nation,
>      o_year,
>      sum(amount) as sum_profit
> from
>      (
>          select
>              n_name as nation,
>              extract(year from o_orderdate) as o_year,
>              l_extendedprice * (1 - l_discount) - ps_supplycost *
> l_quantity as amount
>          from
>              part,
>              supplier,
>              lineitem,
>              partsupp,
>              orders,
>              nation
>          where
>              s_suppkey = l_suppkey
>              and ps_suppkey = l_suppkey
>              and ps_partkey = l_partkey
>              and p_partkey = l_partkey
>              and o_orderkey = l_orderkey
>              and s_nationkey = n_nationkey
>              and p_name like '%orchid%'
>      ) as profit
> group by
>      nation,
>      o_year
> order by
>      nation,
>      o_year desc
>




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From: Fabio Pardi
Date:
Subject: Re: Why HDD performance is better than SSD in this case
From: Neto pr
Date:
Subject: Re: HDD vs SSD without explanation