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https://issues.apache.org/jira/browse/SPARK-2155?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Michael Armbrust updated SPARK-2155:
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Priority: Minor (was: Major)
> 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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