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https://issues.apache.org/jira/browse/SPARK-15076?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Apache Spark reassigned SPARK-15076:
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Assignee: (was: Apache Spark)
> 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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