we've had the same experience here - with older SATA 2 (3Gbps) - in spite of SSD having no spin latency, the bus speed itself was half of the SAS-2 (6Gbps) we were using at the time which negated SSD perf in this area. HDD was about the same perf as SSD for us.
Biran On Mon, Jan 15, 2018 at 1:32 PM, Georg H. <geor...@silentrunner.de> wrote: > > 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 > >
