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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