Github user zhzhan commented on a diff in the pull request:
https://github.com/apache/spark/pull/16068#discussion_r91026433
--- Diff:
sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/HiveUDFSuite.scala
---
@@ -487,6 +488,52 @@ class HiveUDFSuite extends QueryTest with
TestHiveSingleton with SQLTestUtils {
assert(count4 == 1)
sql("DROP TABLE parquet_tmp")
}
+
+ test("Hive Stateful UDF") {
+ withUserDefinedFunction("statefulUDF" -> true, "statelessUDF" -> true)
{
+ sql(s"CREATE TEMPORARY FUNCTION statefulUDF AS
'${classOf[StatefulUDF].getName}'")
+ sql(s"CREATE TEMPORARY FUNCTION statelessUDF AS
'${classOf[StatelessUDF].getName}'")
+ withTempView("inputTable") {
+ val testData = spark.sparkContext.parallelize(
+ (0 until 10) map (x => IntegerCaseClass(1)), 2).toDF()
+ testData.createOrReplaceTempView("inputTable")
+ // Distribute all rows to one partition (all rows have the same
content),
+ // and expected Max(s) is 10 as statefulUDF returns the sequence
number starting from 1.
+ checkAnswer(
+ sql(
+ """
+ |SELECT MAX(s) FROM
+ | (SELECT statefulUDF() as s FROM
+ | (SELECT i from inputTable DISTRIBUTE by i) a
+ | ) b
+ """.stripMargin),
+ Row(10))
+
+ // Expected Max(s) is 5, as there are 2 partitions with 5 rows
each, and statefulUDF
+ // returns the sequence number of the rows in the partition
starting from 1.
+ checkAnswer(
+ sql(
+ """
+ |SELECT MAX(s) FROM
+ | (SELECT statefulUDF() as s FROM
+ | (SELECT i from inputTable) a
+ | ) b
+ """.stripMargin),
+ Row(5))
+
+ // Expected Max(s) is 1, as stateless UDF is deterministic and
replaced by constant 1.
--- End diff --
StatelessUDF is foldable: override def foldable: Boolean =
isUDFDeterministic && children.forall(_.foldable)
ConstantFolding optimizer will replace it with constant:
case e if e.foldable => Literal.create(e.eval(EmptyRow), e.dataType)
Here is the explain(true):
== Parsed Logical Plan ==
'Project [unresolvedalias('MAX('s), None)]
+- 'SubqueryAlias b
+- 'Project ['statelessUDF() AS s#39]
+- 'SubqueryAlias a
+- 'RepartitionByExpression ['i]
+- 'Project ['i]
+- 'UnresolvedRelation `inputTable`
== Analyzed Logical Plan ==
max(s): bigint
Aggregate [max(s#39L) AS max(s)#46L]
+- SubqueryAlias b
+- Project
[HiveSimpleUDF#org.apache.spark.sql.hive.execution.StatelessUDF() AS s#39L]
+- SubqueryAlias a
+- RepartitionByExpression [i#4]
+- Project [i#4]
+- SubqueryAlias inputtable
+- SerializeFromObject
[assertnotnull(assertnotnull(input[0,
org.apache.spark.sql.hive.execution.IntegerCaseClass, true], top level Product
input object), - root class:
"org.apache.spark.sql.hive.execution.IntegerCaseClass").i AS i#4]
+- ExternalRDD [obj#3]
== Optimized Logical Plan ==
Aggregate [max(s#39L) AS max(s)#46L]
+- Project [1 AS s#39L]
+- RepartitionByExpression [i#4]
+- SerializeFromObject [assertnotnull(assertnotnull(input[0,
org.apache.spark.sql.hive.execution.IntegerCaseClass, true], top level Product
input object), - root class:
"org.apache.spark.sql.hive.execution.IntegerCaseClass").i AS i#4]
+- ExternalRDD [obj#3]
== Physical Plan ==
*HashAggregate(keys=[], functions=[max(s#39L)], output=[max(s)#46L])
+- Exchange SinglePartition
+- *HashAggregate(keys=[], functions=[partial_max(s#39L)],
output=[max#48L])
+- *Project [1 AS s#39L]
+- Exchange hashpartitioning(i#4, 5)
+- *SerializeFromObject [assertnotnull(assertnotnull(input[0,
org.apache.spark.sql.hive.execution.IntegerCaseClass, true], top level Product
input object), - root class:
"org.apache.spark.sql.hive.execution.IntegerCaseClass").i AS i#4]
+- Scan ExternalRDDScan[obj#3]
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