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https://issues.apache.org/jira/browse/SPARK-20586?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Apache Spark reassigned SPARK-20586:
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Assignee: Apache Spark (was: Xiao Li)
> Add deterministic and distinctLike to ScalaUDF
> ----------------------------------------------
>
> Key: SPARK-20586
> URL: https://issues.apache.org/jira/browse/SPARK-20586
> Project: Spark
> Issue Type: Bug
> Components: SQL
> Affects Versions: 2.2.0
> Reporter: Xiao Li
> Assignee: Apache Spark
>
> https://hive.apache.org/javadocs/r2.0.1/api/org/apache/hadoop/hive/ql/udf/UDFType.html
> Like Hive UDFType, we should allow users to add the extra flags for ScalaUDF
> too. {{stateful}}/{{impliesOrder}} are not applicable to ScalaUDF. Thus, we
> only add the following two flags.
> - deterministic: Certain optimizations should not be applied if UDF is not
> deterministic. Deterministic UDF returns same result each time it is invoked
> with a particular input. This determinism just needs to hold within the
> context of a query.
> - distinctLike: A UDF is considered distinctLike if the UDF can be evaluated
> on just the distinct values of a column. Examples include min and max UDFs.
> This information is used by metadata-only optimizer.
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