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Posted to issues@spark.apache.org by "Xiao Li (JIRA)" <ji...@apache.org> on 2017/05/03 16:54:04 UTC

[jira] [Created] (SPARK-20586) Add deterministic and distinctLike to ScalaUDF

Xiao Li created SPARK-20586:
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             Summary: 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: Xiao Li


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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