org.apache.spark.sql.catalyst.expressions.aggregate.Count.scala Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.spark.sql.catalyst.expressions.aggregate
import org.apache.spark.sql.catalyst.dsl.expressions._
import org.apache.spark.sql.catalyst.expressions._
import org.apache.spark.sql.types._
/**
* Base class for all counting aggregators.
*/
abstract class CountLike extends DeclarativeAggregate {
override def nullable: Boolean = false
// Return data type.
override def dataType: DataType = LongType
protected lazy val count = AttributeReference("count", LongType, nullable = false)()
override lazy val aggBufferAttributes = count :: Nil
override lazy val initialValues = Seq(
/* count = */ Literal(0L)
)
override lazy val mergeExpressions = Seq(
/* count = */ count.left + count.right
)
override lazy val evaluateExpression = count
override def defaultResult: Option[Literal] = Option(Literal(0L))
}
// scalastyle:off line.size.limit
@ExpressionDescription(
usage = """
_FUNC_(*) - Returns the total number of retrieved rows, including rows containing null.
_FUNC_(expr[, expr...]) - Returns the number of rows for which the supplied expression(s) are all non-null.
_FUNC_(DISTINCT expr[, expr...]) - Returns the number of rows for which the supplied expression(s) are unique and non-null.
""")
// scalastyle:on line.size.limit
case class Count(children: Seq[Expression]) extends CountLike {
override lazy val updateExpressions = {
val nullableChildren = children.filter(_.nullable)
if (nullableChildren.isEmpty) {
Seq(
/* count = */ count + 1L
)
} else {
Seq(
/* count = */ If(nullableChildren.map(IsNull).reduce(Or), count, count + 1L)
)
}
}
}
object Count {
def apply(child: Expression): Count = Count(child :: Nil)
}