https://community.cloudera.com/t5/Support-Questions/Tez-mapper-Slow-Read-from-S3/m-p/311630#M224763 <P>thanks&nbsp;<a href="https://community.cloudera.com/t5/user/viewprofilepage/user-id/33732">@Prakashcit</a>&nbsp; looks the issue with timestamp column, we have int96 format timestamp column with millisecond precision and that performance is 10 time slower compared to a parquet with same column as string value or even with stripped of millisecond timestamp column. We are still investigating what's causing this behavior.</P><P>&nbsp;</P><P>For example a parquet with 2 columns date_time and value,&nbsp;</P><P>Query with timestamp column with milliseconds</P><P>----------------------------------------------------------------------------------------------<BR />VERTICES MODE STATUS TOTAL COMPLETED RUNNING PENDING FAILED KILLED<BR />----------------------------------------------------------------------------------------------<BR />Map 1 .......... llap SUCCEEDED 10 10 0 0 0 0<BR />Reducer 2 ...... llap SUCCEEDED 1 1 0 0 0 0<BR />----------------------------------------------------------------------------------------------<BR />VERTICES: 02/02 [==========================&gt;&gt;] 100% ELAPSED TIME: 179.45 s</P><P>&nbsp;</P><P>query with timestamp column value as string or timestamp column without milliseconds</P><P>----------------------------------------------------------------------------------------------<BR />VERTICES MODE STATUS TOTAL COMPLETED RUNNING PENDING FAILED KILLED<BR />----------------------------------------------------------------------------------------------<BR />Map 1 .......... llap SUCCEEDED 9 9 0 0 0 0<BR />Reducer 2 ...... llap SUCCEEDED 1 1 0 0 0 0<BR />----------------------------------------------------------------------------------------------<BR />VERTICES: 02/02 [==========================&gt;&gt;] 100% ELAPSED TIME: 13.77 s<BR />----------------------------------------------------------------------------------------------</P> Wed, 17 Feb 2021 18:25:35 GMT ARP 2021-02-17T18:25:35Z