On Mon, Oct 29, 2018 at 1:52 AM, Phil Florent wrote: Hi, thank you for comments.
>Yes you will be able to solve bottlenecks with sampling. In interactive mode, >a 1s interval is probably too large. I use 0s1 - 0s01 with my tool and it is >normally OK. With the tool you are using, can you sample at intervals shorter than 1 second? If you can, you can get enough sampling number and you can also acquire short events. >Since grafana is now able to connect directly to a postgresql source, I use it >to display the information collected from pg_stat_activity and psutil ( e.g >https://pgphil.ovh/traqueur_dashboard_02.php page is written in french but >panels are in english) It is wonderful to visualize. Especially for beginners like me. >Other DB have accumulated statistics but you can notice that sampling is also >their most modern method. >E.g Oracle DB : 20 years ago you already had tools like "utlbstat/utlestat" . >Then you had "statspack". Those tools were based on accumulated statistics and >the reports were based on differences between 2 points. It was useful to solve >major problems but it was limited and not precise enough in many cases. >The preferred feature to identify bottlenecks in the Oracle world is now ASH >(active session history). It can help with major problems, specific problems >AND it can identify short blockages. >Too bad it is licensed as an option of their Enterprise Edition but similar >tools exist and they are also based on sampling of the activity. >With the "official" ASH, sampling and archiving are done internally and you >have a circular memory zone dedicated to the feature. Hence the overhead is >lower but that's all. >The most advanced interactive tool is called "snapper" and it is also based on >sampling. Thanks. I will check it. The current bottleneck survey method, from sampling, I can know the number (ratio) of waiting events. Then, investigate from those with a high number of times (ratio). Do you agree with this recognition? --------------------------------------- Naoki, Yotsunaga.
