On Wed, Feb 14, 2018 at 12:17 PM, Rafia Sabih <rafia.sa...@enterprisedb.com> wrote:
> On Tue, Feb 13, 2018 at 6:21 PM, Jeevan Chalke < > jeevan.cha...@enterprisedb.com> wrote: > >> >> I see that partition-wise aggregate plan too uses parallel index, am I >> missing something? >> >> > You're right, I missed that, oops. > >> >>> 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. >> >> Yeah strange it is. > Off-list I have asked Rafia to provide me the perf machine access where she is doing this bench-marking to see what's going wrong. Thanks Rafia for the details. What I have observed that, there are two sources, one with HEAD and other with HEAD+PWA. However the configuration switches were different. Sources with HEAD+PWA has CFLAGS="-ggdb3 -O0" CXXFLAGS="-ggdb3 -O0" flags in addition with other sources. i.e. HEAD+PWA is configured with debugging/optimization enabled which account for the slowness. I have run EXPLAIN for these three queries on both the sources having exactly same configuration switches and I don't find any slowness with PWA patch-set. Thus, it will be good if you re-run the benchmark by keeping configuration switches same on both the sources and share the results. Thanks > However, do you see similar behaviour with patches applied, >> "enable_partition_wise_agg = on" and "enable_partition_wise_agg = off" ? >> > > I tried that for query 18, with patch and enable_partition_wise_agg = > off, query completes in some 270 secs. You may find the explain analyse > output for it in the attached file. I noticed that on head the query plan > had parallel hash join however with patch and no partition-wise agg it is > using nested loop joins. This might be the issue. > >> >> Also, does rest of the queries perform better with partition-wise >> aggregates? >> >> > As far as this setting goes, there wasn't any other query using > partition-wise-agg, so, no. > > BTW, just an FYI, this experiment is on scale factor 20. > > -- > Regards, > Rafia Sabih > EnterpriseDB: http://www.enterprisedb.com/ > -- Jeevan Chalke Technical Architect, Product Development EnterpriseDB Corporation The Enterprise PostgreSQL Company
