Re: HDD vs SSD without explanation

Hello Neto

Am 14.01.2018 um 21:44 schrieb Neto pr:
> Dear all
>
> Someone help me analyze the two execution plans below (Explain ANALYZE 
> used), is the  query 9 of TPC-H benchmark [1].
> I'm using a server HP Intel Xeon 2.8GHz/4-core - Memory 8GB HDD SAS 
> 320GB 15 Krpm AND SSD Sansung EVO 500GB.
> My DBMS parameters presents in postgresql.conf is default, but in SSD 
> I have changed random_page_cost = 1.0.
>
you are comparing a SAS Drive against a SATA SSD. Their interfaces serve 
a completely different bandwidth.
While a SAS-3 device does 12 Gbit/s  SATA-3 device  is only able to 
transfer 6 Gbit/s  (a current SAS-4 reaches 22.5 Gbit/s)
Do a short research on SAS vs SATA and then use a SAS SSD for comparison :)

regards
Georg