https://community.cloudera.com/t5/Support-Questions/kudu-scan-very-slow/m-p/85258#M11684 <P><SPAN>kudu1.7.0 in cdh 5.15</SPAN></P><P><SPAN>3 master nodes, 4c32g, ubuntu16.04&nbsp;</SPAN><BR /><SPAN>3 data nodes, 8c64g, 1.8T ssd, ubuntu16.04</SPAN></P><P>&nbsp;</P><P><SPAN>It is a small table: project_spot, 5.93K records, 38 columns</SPAN></P><P><SPAN>I found some slow sql on it（more than 400ms）, most time spend on&nbsp;</SPAN>MaterializeTupleTime&nbsp;</P><P>So i check the scan page on kudu tablet server web ui, and found this:</P><P><span class="lia-inline-image-display-wrapper lia-image-align-inline" image-alt="kuduscan.png" style="width: 600px;"><img src="https://community.cloudera.com/t5/image/serverpage/image-id/5228iDB6A3F5E442E0FF4/image-size/large?v=v2&amp;px=999" role="button" title="kuduscan.png" alt="kuduscan.png" /></span></P><P>It is a very small scan, but spend 423ms, why?</P><P>&nbsp;</P><P>More information:</P><P>I check the io performance on all data nodes using fio, no problem found:</P><PRE>read : io=6324.4MB, bw=647551KB/s, iops=161887, runt= 10001msec</PRE><P>There are 3 data nodes, only&nbsp;data02 has the problem.</P><P>I reboot the tablet server on data02, not work</P> Fri, 16 Sep 2022 14:05:15 GMT huaj 2022-09-16T14:05:15Z