https://community.cloudera.com/t5/Support-Questions/Impala-3-2-0-performance-degradation-while-querying-views/m-p/301620#M220781 <P>Additional info: pretty much all the difference in runtime is due to query compilation and planning. The actual execution time is the same for tables and views.</P><P>&nbsp;</P><P>I also don't have any joins, just selection of a column and a simple aggregation. For example:</P><DIV><DIV><SPAN>SELECT</SPAN><SPAN>&nbsp;</SPAN><SPAN>sum</SPAN><SPAN>(c1)&nbsp;</SPAN><SPAN>from</SPAN><SPAN>&nbsp;table_name</SPAN><SPAN>;</SPAN></DIV><DIV>&nbsp;</DIV><DIV><SPAN>The same query over a view created based on a selection of all columns of table_name (400 columns) takes much more time.</SPAN></DIV><DIV><SPAN>The same query over a view created based on a selection of only "c1" column from table_name does not suffer from this penalty in runtime.</SPAN></DIV></DIV> Tue, 18 Aug 2020 16:40:02 GMT PauloRC 2020-08-18T16:40:02Z