I executed the sum and count query on my table where the cluster has three nodes. I found that the sum query is not well parallel executed(not all the three nodes get high load when executing the sum query) and the cpu load is very high while the memory load is very low(the machines have 16 cores and 16GB memory). My sum query on the 12 million data sets takes about 2 minutes and a half time.
So my question is that is there any optimization advice that I can use to improve the query performance and maximize the usage of my machines, what ever the configuration or the table ddl.
Any replies is appreciated.