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https://issues.apache.org/jira/browse/SPARK-14939?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Dongjoon Hyun updated SPARK-14939:
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Summary: Add FoldablePropagation optimizer (was: [SPARK-14939][SQL] Add
FoldablePropagation optimizer)
> Add FoldablePropagation optimizer
> ---------------------------------
>
> Key: SPARK-14939
> URL: https://issues.apache.org/jira/browse/SPARK-14939
> Project: Spark
> Issue Type: Improvement
> Components: Optimizer
> Reporter: Dongjoon Hyun
>
> This issue aims to add new FoldablePropagation optimizer that propagates
> foldable expressions up over the logical plan nodes. Currently, ORDER BY,
> GROUP BY, Nested-SELECT clauses are supported, and aliases and ordinal
> expressions are the main target to be transformed after propagation. Other
> optimizations will take advantage of the propagated foldable expressions:
> e.g. EliminateSorts optimizer now can handle Case 2 and 3. (Case 1 is the
> previous implementation.)
> 1. Literals and foldable expression, e.g. "ORDER BY 1.0, 'abc', Now()"
> 2. Foldable ordinals, e.g. "SELECT 1.0, 'abc', Now() ORDER BY 1, 2, 3"
> 3. Foldable aliases, e.g. "SELECT 1.0 x, 'abc' y, Now() z ORDER BY x, y, z"
> **Before**
> {code}
> scala> sql("SELECT 1.0, Now() x ORDER BY 1, x").explain
> == Physical Plan ==
> WholeStageCodegen
> : +- Sort [1.0#5 ASC,x#0 ASC], true, 0
> : +- INPUT
> +- Exchange rangepartitioning(1.0#5 ASC, x#0 ASC, 200), None
> +- WholeStageCodegen
> : +- Project [1.0 AS 1.0#5,1461873043577000 AS x#0]
> : +- INPUT
> +- Scan OneRowRelation[]
> {code}
> **After**
> {code}
> scala> sql("SELECT 1.0, Now() x ORDER BY 1, x").explain
> == Physical Plan ==
> WholeStageCodegen
> : +- Project [1.0 AS 1.0#5,1461873079484000 AS x#0]
> : +- INPUT
> +- Scan OneRowRelation[]
> {code}
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