[jira] [Created] (DRILL-491) Support project push-down into scan operator

["Jinfeng Ni (JIRA)" <ji...@apache.org>]

Jinfeng Ni created DRILL-491:
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             Summary: Support project push-down into scan operator
                 Key: DRILL-491
                 URL: https://issues.apache.org/jira/browse/DRILL-491
             Project: Apache Drill
          Issue Type: Bug
            Reporter: Jinfeng Ni
            Assignee: Jinfeng Ni


Currently, the scan operator will read all the columns from the data source, and pass all the columns to down-stream operator. 

In order to improve performance of Drill query, we should instead push the project operation into scan operator.  The scan operator will take as an input a list of columns required to retrieve. If the query only refers a subset of columns, the scan operator will only have to retrieve values for the column in the list. 

It's expected to see performance improvement once project push-down is supported. 




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