I have submitted the following issue, https://issues.apache.org/jira/browse/IMPALA-10789 <https://issues.apache.org/jira/browse/IMPALA-10789>
In some cases, the performance is better that early materialize expressions in ScanNode. For example, SELECT SUM(col), COUNT(col), MIN(col), MAX(col) FROM ( SELECT CAST(regexp_extract(string_col, '(\\d+)', 0) AS bigint) col FROM functional_parquet.alltypesagg ) t The expression only needs to be evaluated once if materialize expressions in ScanNode. I have roughly implemented this feature and the performance has improved significantly. I would like to discuss whether this feature can be contributed. Thanks! Xianqing
