Hi Georg,
Your answer I believe has revealed the real problem.
I looked at the specification of my SATA SSD, and from my SAS HDD, I
saw that the SAS has 12 Gb/s versus 6 Gb/s from the SSD

SSD: Samsung 500 GB SATA III 6Gb/s - Model: 850 Evo

HDD: HPE 300GB 12G SAS Part-Number: 737261-B21

I saw that the SAS band is double, and because of that reason the
difference in performance occurred.

Another question, if I compare the disk below HDD SAS that has a
transfer rate of 6Gb/s equal to the SSD SATA 6Gb/s, do you think the
SSD would be more agile in this case?
HDD: HP 450GB 6G SAS 15K rpm LFF (3.5-inch) Part-Number: 652615-B21

best Regards

2018-01-15 16:32 GMT-02:00 Georg H. <geor...@silentrunner.de>:
> 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

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