cloud-fan commented on a change in pull request #30745: URL: https://github.com/apache/spark/pull/30745#discussion_r583481849
########## File path: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Product.scala ########## @@ -0,0 +1,74 @@ +/* + * 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.analysis.TypeCheckResult +import org.apache.spark.sql.catalyst.dsl.expressions._ +import org.apache.spark.sql.catalyst.expressions.{AttributeReference, Expression, ImplicitCastInputTypes, Literal} +import org.apache.spark.sql.catalyst.util.TypeUtils +import org.apache.spark.sql.types.{AbstractDataType, DataType, DoubleType} + + +/** Multiply numerical values within an aggregation group */ +case class Product(child: Expression) + extends DeclarativeAggregate with ImplicitCastInputTypes { + + override def children: Seq[Expression] = child :: Nil + + override def nullable: Boolean = true + + override def dataType: DataType = resultType + + override def inputTypes: Seq[AbstractDataType] = Seq(DoubleType) + + override def checkInputDataTypes(): TypeCheckResult = + TypeUtils.checkForNumericExpr(child.dataType, "function product") + + private val resultType = DoubleType + + private lazy val product = AttributeReference("product", resultType)() + + private lazy val one = Literal(1.0, resultType) + + override lazy val aggBufferAttributes = product :: Nil + + override lazy val initialValues: Seq[Expression] = + Seq(Literal(null, resultType)) + + override lazy val updateExpressions: Seq[Expression] = { + // Treat the result as null until we have seen at least one child value, + // whereupon the previous product is promoted to being unity. + // Each child value is implicitly multiplied by a scaling factor + // (1.0 by default) so that the client has some control over overflow Review comment: sorry I may missed something. Why do we need to multiple by 1.0? double * 1.0 means noop IIUC. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
