[jira] [Assigned] (DRILL-3754) Remove redundancy in run-time generated code for common column references.

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

     [ https://issues.apache.org/jira/browse/DRILL-3754?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Jinfeng Ni reassigned DRILL-3754:
---------------------------------

    Assignee: Jinfeng Ni

> Remove redundancy in run-time generated code for common column references. 
> ---------------------------------------------------------------------------
>
>                 Key: DRILL-3754
>                 URL: https://issues.apache.org/jira/browse/DRILL-3754
>             Project: Apache Drill
>          Issue Type: Bug
>          Components: Execution - Codegen
>    Affects Versions: 1.1.0
>            Reporter: Jinfeng Ni
>            Assignee: Jinfeng Ni
>             Fix For: Future
>
>         Attachments: 0002-DRILL-3754-Reduce-redundancy-in-run-time-generated-c.patch
>
>
> When a operator (Filter, project) has expression which refer one same field multiple times, Drill will initialize a value vector and do value holder assignment   for each field reference in the run-time generated code.  The redundancy might impact the expression evaluation, after the compiled code is executed over large number of incoming rows.
> This has been seen in recent performance issue reported on the drill user list,  where the query contains multiple multiple in list filter conditions. 
> In this JIRA, we'll remove the redundancy for the common field reference, so that only one initialization and assignment happen in the run-time generated code.



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