On Tue, Feb 13, 2018 at 12:37 PM, Rafia Sabih <rafia.sa...@enterprisedb.com> wrote:
> > I was testing this patch for TPC-H benchmarking and came across following > results, > Thanks Rafia for testing this with TPC-H benchmarking. > > Q1 completes in 229 secs with patch and in 66 secs without it. It looks > like with this patch the time of parallel seq scan itself is elevated for > some of the partitions. Notice for partitions, lineitem_3, lineitem_7, > lineitem_10, and linietem_5 it is some 13 secs which was somewhere around 5 > secs on head. > > Q6 completes in some 7 secs with patch and it takes 4 secs without it. > This is mainly caused because with the new parallel append, the parallel > operator below it (parallel index scan in this case) is not used, however, > on head it was the append of all the parallel index scans, which was saving > quite some time. > I see that partition-wise aggregate plan too uses parallel index, am I missing something? > > Q18 takes some 390 secs with patch and some 147 secs without it. > This looks strange. This patch set does not touch parallel or seq scan as such. I am not sure why this is happening. All these three queries explain plan shows much higher execution time for parallel/seq scan. However, do you see similar behaviour with patches applied, "enable_partition_wise_agg = on" and "enable_partition_wise_agg = off" ? Also, does rest of the queries perform better with partition-wise aggregates? > > The experimental setup for these tests is as follows, > work_mem = 500MB > shared_buffers = 10GB > effective_cache_size = 4GB > seq_page_cost = random+page_cost = 0.01 > enable_partition_wise_join = off > > Partitioning info: > Total 10 partitions on tables - lineitem and orders each with partitioning > key being l_orderkey and o_orderkey respectively. > > Please find the attached file for explain analyse outputs of each of the > reported query. > -- > Regards, > Rafia Sabih > EnterpriseDB: http://www.enterprisedb.com/ > -- Jeevan Chalke Technical Architect, Product Development EnterpriseDB Corporation The Enterprise PostgreSQL Company
