Hello, Dmitry! On 06/23/2014 04:15 AM, Dmitry Yemanov wrote: > 21.06.2014 01:52, Nikolay Samofatov wrote: >> I attach patch for this functionality to give you an idea of >> implementation. It depends on a couple other changes so it doesn't apply >> to FB2.5 cleanly. > The first thing I'm interested in is the performance impact in OLTP > tests similar to TPCC (with lots of short concurrent requests). Do you > have any numbers? If the difference is noticable, then I believe the new > mode should not become a default one, it should be turned on expicitly.
I didn't run TPCC, but I created some artificial tests to measure overheads of new logic. Most tests show no statistically significant difference. In various tests, the worst I have seen was 2% slowdown when doing count(*) on a fully cached table with 2 integers. Some tests (namely, execute statement in autonomous transaction in a loop) show statistically significant speed up of up to 4%. I had to rewrite the code a few times, and analyze it with a profiler to achieve this result. If you can point me to a situation when new code is, say, more than 5% slower than old logic in a test (even totally artificial one), I am willing to fix it. > > Also, I believe it should be a TPB setting (read-committed specific, > similar to rec_version / no_rec_version) rather than a config option. I really don't think enabling bugfix should be a TPB option. I explained to Vlad in more detail in my previous letter. > > > Dmitry > > Nikolay Samofatov ------------------------------------------------------------------------------ HPCC Systems Open Source Big Data Platform from LexisNexis Risk Solutions Find What Matters Most in Your Big Data with HPCC Systems Open Source. Fast. Scalable. Simple. Ideal for Dirty Data. Leverages Graph Analysis for Fast Processing & Easy Data Exploration http://p.sf.net/sfu/hpccsystems Firebird-Devel mailing list, web interface at https://lists.sourceforge.net/lists/listinfo/firebird-devel
