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Posted to issues@spark.apache.org by "Liang-Chi Hsieh (Jira)" <ji...@apache.org> on 2019/09/06 18:20:00 UTC

[jira] [Created] (SPARK-29013) Structurally equivalent subexpression elimination

Liang-Chi Hsieh created SPARK-29013:
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             Summary: Structurally equivalent subexpression elimination
                 Key: SPARK-29013
                 URL: https://issues.apache.org/jira/browse/SPARK-29013
             Project: Spark
          Issue Type: New Feature
          Components: SQL
    Affects Versions: 3.0.0
            Reporter: Liang-Chi Hsieh


We do semantically equivalent subexpression elimination in SparkSQL. However, for some expressions that are not semantically equivalent, but structurally equivalent, current subexpression elimination generates too many similar functions. These functions share same computation structure but only differ in input slots of current processing row.

For such expressions, we can generate just one function, and pass in input slots during runtime.

It can reduce the length of generated code text, and save compilation time.

 



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