Description of problem: In scale environments the sampling process took around 25s. We want to lower it below 15s in order to run the sampling every 15s. Version-Release number of selected component (if applicable): 4.0 How reproducible: Steps to Reproduce: 1.Install engine +dwh and set up a scale environment 2.Run dwh in debug mode and with sampling intercal set to 15. 3.Check the sampling time in the dwh log file. Actual results: The sampling takes around 25 seconds Expected results: Should be under15s. Additional info:
Created attachment 1189126 [details] sample query duration values
Tested on 4.0.2-1 DWH (App & DB) on same tier as Engine App Dataset: hosts: 541 vms: 6322 Standard disk used for Database. Without postgres tuning sample query finishes in 30-39s. With tuned postgres sample query reduced to 5-6s. Some sample query degradation occurs during delete jobs but only by a few additional seconds still remaining under 15s for most queries. While we tune a few settings, in order to see sample query return under 15s please set: checkpoint_segments = 128 checkpoint_completion_target = 0.9 Further information available: https://mojo.redhat.com/docs/DOC-1089988 Last Sample values parsed, and attached.