[jira] [Updated] (SPARK-17480) CompressibleColumnBuilder inefficiently call gatherCompressibilityStats

["Ergin Seyfe (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/SPARK-17480?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Ergin Seyfe updated SPARK-17480:
--------------------------------
    Description: 
When we profile one of our Spark jobs we saw that:

6.24% of the CPU is spend on List.length.
Scala List's length method is O(N) => https://github.com/scala/scala/blob/2.10.x/src/library/scala/collection/LinearSeqOptimized.scala#L36

Since we loop this method becomes O(N^2)

  was:
When we profile one of our Spark jobs we saw that:

6.24% of the CPU is spend on List.length.
Scala List's length method is O (N) => https://github.com/scala/scala/blob/2.10.x/src/library/scala/collection/LinearSeqOptimized.scala#L36

Since we loop this method becomes O(N^2)


> CompressibleColumnBuilder inefficiently call gatherCompressibilityStats 
> ------------------------------------------------------------------------
>
>                 Key: SPARK-17480
>                 URL: https://issues.apache.org/jira/browse/SPARK-17480
>             Project: Spark
>          Issue Type: Improvement
>          Components: SQL
>            Reporter: Ergin Seyfe
>            Priority: Minor
>
> When we profile one of our Spark jobs we saw that:
> 6.24% of the CPU is spend on List.length.
> Scala List's length method is O(N) => https://github.com/scala/scala/blob/2.10.x/src/library/scala/collection/LinearSeqOptimized.scala#L36
> Since we loop this method becomes O(N^2)



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