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From "Apache Spark (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (SPARK-15076) Improve ConstantFolding optimizer to use integral associative property
Date Mon, 02 May 2016 22:42:13 GMT

    [ https://issues.apache.org/jira/browse/SPARK-15076?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15267657#comment-15267657
] 

Apache Spark commented on SPARK-15076:
--------------------------------------

User 'dongjoon-hyun' has created a pull request for this issue:
https://github.com/apache/spark/pull/12850

> Improve ConstantFolding optimizer to use integral associative property
> ----------------------------------------------------------------------
>
>                 Key: SPARK-15076
>                 URL: https://issues.apache.org/jira/browse/SPARK-15076
>             Project: Spark
>          Issue Type: Improvement
>          Components: Optimizer
>            Reporter: Dongjoon Hyun
>
> This issue improves `ConstantFolding` optimizer by taking advantage of integral associative
property. Currently, `ConstantFolding` works like the following.
> 1) Can optimize `1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + a` into `45 + a`.
> 2) Cannot optimize `a + 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9`.
> This issue enables `ConstantFolding` to handle Case 2 for *Add/Multiply* expression whose
data types are `ByteType`, `ShortType`, `IntegerType`, and `LongType`. The followings are
the plan comparision between `before` and `after` this issue.
> **Before**
> {code}
> scala> sql("select a+1+2+3+4+5+6+7+8+9 from (select explode(array(1)) a)").explain
> == Physical Plan ==
> WholeStageCodegen
> :  +- Project [(((((((((a#7 + 1) + 2) + 3) + 4) + 5) + 6) + 7) + 8) + 9) AS (((((((((a
+ 1) + 2) + 3) + 4) + 5) + 6) + 7) + 8) + 9)#8]
> :     +- INPUT
> +- Generate explode([1]), false, false, [a#7]
>    +- Scan OneRowRelation[]
> {code}
> **After**
> {code}
> scala> sql("select a+1+2+3+4+5+6+7+8+9 from (select explode(array(1)) a)").explain
> == Physical Plan ==
> WholeStageCodegen
> :  +- Project [(a#7 + 45) AS (((((((((a + 1) + 2) + 3) + 4) + 5) + 6) + 7) + 8) + 9)#8]
> :     +- INPUT
> +- Generate explode([1]), false, false, [a#7]
>    +- Scan OneRowRelation[]
> {code}



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