On Sun, Nov 24, 2019 at 8:52 AM Mariel Cherkassky < mariel.cherkas...@gmail.com> wrote:
> Hey Andrew, > It seems that changing this parameter worked for me. > Setting it to zero means that there wont be any parallel workers for one > query right ? > Is it something familiar this problem with the gatherers ? > Your example would not be using parallel workers anyway, regardless of the setting of max_parallel_workers_per_gather, so I don't see how changing this could have worked for you. Unless you mean it worked in your full test, rather than in your test case. I doubt your test case benchmarking was very reliable to start with, you only show a single execution and didn't indicate you had more unshown ones. If I do more credible benchmarking, I do get a performance regression but it closer is to 16% than to 3 fold. And it doesn't depend on the setting of max_parallel_workers_per_gather. I doubt a regression of this size is even worth investigating. pgbench -T300 -P5 -f <(echo "select count(*) from test1") -p 9912 -n -M prepared Cheers, Jeff
