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Posted to issues@spark.apache.org by "Apache Spark (JIRA)" <ji...@apache.org> on 2015/05/07 14:52:59 UTC

[jira] [Commented] (SPARK-2155) Support effectful / non-deterministic key expressions in CASE WHEN statements

    [ https://issues.apache.org/jira/browse/SPARK-2155?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14532561#comment-14532561 ] 

Apache Spark commented on SPARK-2155:
-------------------------------------

User 'cloud-fan' has created a pull request for this issue:
https://github.com/apache/spark/pull/5979

> Support effectful / non-deterministic key expressions in CASE WHEN statements
> -----------------------------------------------------------------------------
>
>                 Key: SPARK-2155
>                 URL: https://issues.apache.org/jira/browse/SPARK-2155
>             Project: Spark
>          Issue Type: Bug
>          Components: SQL
>            Reporter: Zongheng Yang
>            Priority: Minor
>
> Currently we translate CASE KEY WHEN to CASE WHEN, hence incurring redundant evaluations of the key expression. Relevant discussions here: https://github.com/apache/spark/pull/1055/files#r13784248
> If we are very in need of support for effectful key expressions, at least we can resort to the baseline approach of having both CaseWhen and CaseKeyWhen as expressions, which seem to introduce much code duplication (e.g. see https://github.com/concretevitamin/spark/blob/47d406a58d129e5bba68bfadf9dd1faa9054d834/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/predicates.scala#L216 for a sketch implementation). 



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