[jira] [Updated] (SPARK-15764) Replace n^2 loop in BindReferences

["Reynold Xin (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/SPARK-15764?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Reynold Xin updated SPARK-15764:
--------------------------------
    Issue Type: Sub-task  (was: Improvement)
        Parent: SPARK-15852

> Replace n^2 loop in BindReferences
> ----------------------------------
>
>                 Key: SPARK-15764
>                 URL: https://issues.apache.org/jira/browse/SPARK-15764
>             Project: Spark
>          Issue Type: Sub-task
>          Components: SQL
>            Reporter: Josh Rosen
>            Assignee: Josh Rosen
>             Fix For: 2.0.0
>
>
> BindReferences contains a n^2 loop which causes performance issues when operating over large schemas: to determine the ordinal of an input, we perform a linear scan over the {{input}} array. Because {{input}} can sometimes be a List, the call to {{input(ordinal).nullable}} can also be O(n).
> Instead of performing a linear scan, we can convert the input into an array and build a hash map to map from expression ids to ordinals. The greater up-front cost of the map construction is offset by the fact that an expression can contain multiple attribute references, so the cost of the map construction is amortized across a number of lookups.



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