On Thu, 20 Dec 2018 at 20:17, Gavin Flower <gavinflo...@archidevsys.co.nz> wrote: > Looking at the normalized standard deviations, the patched results have > a higher than 5% chance of being better simply by chance. I suspect > that you have made an improvement, but the statistics are not convincing.
Yeah, I'd hoped that I could have gotten a better signal to noise ratio by running the test many times, but you're right. That was on my laptop. I've run the test again on an AWS instance and the results seem to be a bit more stable. Same table with 1 int column and 100m rows. statistics set to 10. Unpatched postgres=# analyze a; Time: 38.248 ms Time: 35.185 ms Time: 35.067 ms Time: 34.879 ms Time: 34.816 ms Time: 34.558 ms Time: 34.722 ms Time: 34.427 ms Time: 34.214 ms Time: 34.301 ms Time: 35.751 ms Time: 33.993 ms Time: 33.880 ms Time: 33.617 ms Time: 33.381 ms Time: 33.326 ms Patched: postgres=# analyze a; Time: 34.421 ms Time: 33.523 ms Time: 33.230 ms Time: 33.678 ms Time: 32.987 ms Time: 32.914 ms Time: 33.165 ms Time: 32.707 ms Time: 32.645 ms Time: 32.814 ms Time: 32.082 ms Time: 32.143 ms Time: 32.310 ms Time: 31.966 ms Time: 31.702 ms Time: 32.089 ms Avg +5.72%, Median +5.29% -- David Rowley http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services