[jira] [Commented] (HIVE-21465) Introduce a base abstract VectorExpression to eliminate further code duplications

["Laszlo Bodor (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HIVE-21465?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16795201#comment-16795201 ] 

Laszlo Bodor commented on HIVE-21465:
-------------------------------------

uploaded an initial version into review board
https://reviews.apache.org/r/70231/

this introduces generic BaseVectorExpression, which can ensure correct input / output columnvector types at compile time

> Introduce a base abstract VectorExpression to eliminate further code duplications
> ---------------------------------------------------------------------------------
>
>                 Key: HIVE-21465
>                 URL: https://issues.apache.org/jira/browse/HIVE-21465
>             Project: Hive
>          Issue Type: Bug
>            Reporter: Laszlo Bodor
>            Assignee: Laszlo Bodor
>            Priority: Major
>         Attachments: HIVE-21465.01.patch
>
>
> In vectorized expressions, from time to time, I see a similar/same logic to be repeated, which always consists of some stuff like:
> 1. some inner loops (even the comments are the same)
> {code}
> grep -iRH "Set isNull before call in case it changes it mind" | grep "ql/src/java/org/apache/hadoop/hive/ql/exec/vector/expressions/"
> {code}
> 2. call to an actual "business logic" function ==> 1 line which could be abstracted... and it has been abstracted in hive codebase in n different cases.
> However, an abstract BaseVectorExpression would not force anybody to extend it instead of VectorExpression and not copy the code again, but it could be a good start and an example.



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