https://community.cloudera.com/t5/Support-Questions/kudu-scan-very-slow/m-p/85367#M11685 <P>You might be able to find a trace of the ScanRequest RPC in the /rpcz endpoint of the web UI. Try running the scan and, if you observe it is slow, looking at /rpcz for the matching trace.</P><P>&nbsp;</P><P>If that's too difficult, you can get all the traces dumped into the INFO log using the flag -rpc_dump_all_traces. Naturally this is very verbose on a busy server, but if you use the kudu tserver set_flag command you can turn the flag on and then turn it off a few seconds later, giving just enough time to capture the scan if you coordinate running the scan with turning on tracing. It's safe to change the flag at runtime in this way.</P><P>&nbsp;</P><P>If you get a trace, please copy paste it in a reply here. It will help us understand where time is being spent.</P><P>&nbsp;</P><P>You could also try gathering a trace of the tablet server when the slow scan runs. If you upload the trace file I can take a look at it.</P><P>&nbsp;</P><P>See&nbsp;<A href="https://kudu.apache.org/docs/troubleshooting.html#kudu_tracing" target="_blank">https://kudu.apache.org/docs/troubleshooting.html#kudu_tracing</A> for more information on how to gather traces.</P><P>&nbsp;</P><P>&nbsp;</P> Wed, 23 Jan 2019 20:10:42 GMT wdberkeley 2019-01-23T20:10:42Z