We use benchmarksql to start tpcc test in postgresql 9.3.3.
Before test we set benchmarksql client number about 800. And we increase the hash partitions from 16 to 1024 , in order to reduce the hash partition locks competition.
Can you give the complete invocation parameters for benchmarksql?
How many CPUs/cores do you have?
We expect that after increase the number of partitions, reduces lock competition, TPMC should be increased. But the test results on the contrary, after modified to 1024, TPMC did not increase, but decrease.
Why such result?
Increasing the partition numbers would only help with contention that is due to hash collision. If all of the contention is on, for example, the root block of one index, then increasing the number partitions won't change that, because that block is always going to map to a single partition.
Can you "perf" or some other profiling tool to find where your bottleneck is?