org.apache.spark.sql.catalyst.expressions.aggregate.Min.scala Maven / Gradle / Ivy
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* http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.spark.sql.catalyst.expressions.aggregate
import org.apache.spark.sql.catalyst.analysis.TypeCheckResult
import org.apache.spark.sql.catalyst.dsl.expressions._
import org.apache.spark.sql.catalyst.expressions._
import org.apache.spark.sql.catalyst.util.TypeUtils
import org.apache.spark.sql.types._
@ExpressionDescription(
usage = "_FUNC_(expr) - Returns the minimum value of `expr`.")
case class Min(child: Expression) extends DeclarativeAggregate {
override def children: Seq[Expression] = child :: Nil
override def nullable: Boolean = true
// Return data type.
override def dataType: DataType = child.dataType
override def checkInputDataTypes(): TypeCheckResult =
TypeUtils.checkForOrderingExpr(child.dataType, "function min")
private lazy val min = AttributeReference("min", child.dataType)()
override lazy val aggBufferAttributes: Seq[AttributeReference] = min :: Nil
override lazy val initialValues: Seq[Expression] = Seq(
/* min = */ Literal.create(null, child.dataType)
)
override lazy val updateExpressions: Seq[Expression] = Seq(
/* min = */ least(min, child)
)
override lazy val mergeExpressions: Seq[Expression] = {
Seq(
/* min = */ least(min.left, min.right)
)
}
override lazy val evaluateExpression: AttributeReference = min
}