huaxingao commented on a change in pull request #32049: URL: https://github.com/apache/spark/pull/32049#discussion_r634879199
########## File path: sql/catalyst/src/main/scala/org/apache/spark/sql/sources/aggregates.scala ########## @@ -0,0 +1,38 @@ +/* + * 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.sources + +import org.apache.spark.sql.types.DataType + +// Aggregate Functions in SQL statement. +// e.g. SELECT COUNT(EmployeeID), Max(salary), deptID FROM dept GROUP BY deptID +// aggregateExpressions are (COUNT(EmployeeID), Max(salary)), groupByColumns are (deptID) +case class Aggregation(aggregateExpressions: Seq[Seq[AggregateFunc]], + groupByColumns: Seq[String]) + +abstract class AggregateFunc + +case class Min(column: String, dataType: DataType) extends AggregateFunc +case class Max(column: String, dataType: DataType) extends AggregateFunc Review comment: This is not supported by Parquet and ORC because they don't have these kind of statistics info. For JDBC, I treat this as one Column. I have something like this: ``` private def columnAsString(e: Expression): String = e match { case AttributeReference(name, _, _, _) => name case Cast(child, _, _) => columnAsString (child) case Add(left, right, _) => columnAsString(left) + " + " + columnAsString(right) case Subtract(left, right, _) => columnAsString(left) + " - " + columnAsString(right) case Multiply(left, right, _) => columnAsString(left) + " * " + columnAsString(right) case Divide(left, right, _) => columnAsString(left) + " / " + columnAsString(right) case CheckOverflow(child, _, _) => columnAsString (child) case PromotePrecision(child) => columnAsString (child) case _ => "" } ``` When we do sql("SELECT Max(a+b) FROM t").show, it has: ``` +------------+ |max((a + b))| +------------+ +------------+ ``` I guess it makes sense to treat this as one column? -- 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: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org For additional commands, e-mail: reviews-h...@spark.apache.org
