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
