Re: [HACKERS] Partition-wise aggregation/grouping

 

I was testing this patch for TPC-H benchmarking and came across following results,

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.

Q18 takes some 390 secs with patch and some 147 secs without it. 

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.

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Regards,

Rafia Sabih

EnterpriseDB: http://www.enterprisedb.com/