Re: v17 vs v16 performance comparison

01.08.2024 06:41, Tom Lane wrote:
>
>> But beside that, I've found a separate regression. Bisecting for this degradation:
>> Best pg-src-17--.* worse than pg-src-16--.* by 105.0 percents (356.63 > 173.96): s64da_tpcds.query95
>> Average pg-src-17--.* worse than pg-src-16--.* by 105.2 percents (357.79 > 174.38): s64da_tpcds.query95
>> pointed at f7816aec2.
> I'm not terribly concerned about that.  The nature of planner changes
> like that is that some queries will get worse and some better, because
> the statistics and cost estimates we're dealing with are not perfect.
> It is probably worth drilling down into that test case to understand
> where the planner is going wrong, with an eye to future improvements;
> but I doubt it's something we need to address for v17.

Please find attached two plans for that query [1].
(I repeated the benchmark for f7816aec2 and f7816aec2~1 five times and
made sure that both plans are stable.)

Meanwhile I've bisected another degradation:
Best pg-src-17--.* worse than pg-src-16--.* by 11.3 percents (7.17 > 6.44): job.query6f
and came to the commit b7b0f3f27 again.

[1] https://github.com/swarm64/s64da-benchmark-toolkit/blob/master/benchmarks/tpcds/queries/queries_10/95.sql

Best regards,
Alexander