cloud-fan commented on code in PR #39508: URL: https://github.com/apache/spark/pull/39508#discussion_r1066897375
########## sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/ResolveReferencesInSort.scala: ########## @@ -0,0 +1,81 @@ +/* + * 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.analysis + +import org.apache.spark.sql.catalyst.SQLConfHelper +import org.apache.spark.sql.catalyst.expressions.SortOrder +import org.apache.spark.sql.catalyst.plans.logical.{LogicalPlan, Project, Sort} + +/** + * A virtual rule to resolve [[UnresolvedAttribute]] in [[Sort]]. It's only used by the real + * rule `ResolveReferences`. The column resolution order for [[Sort]] is: + * 1. Resolves the column to [[AttributeReference]] with the output of the child plan. This + * includes metadata columns as well. + * 2. Resolves the column to a literal function which is allowed to be invoked without braces, e.g. + * `SELECT col, current_date FROM t`. + * 3. If the child plan is Aggregate, resolves the column to [[TempResolvedColumn]] with the output + * of Aggregate's child plan. This is to allow Sort to host grouping expressions and aggregate + * functions, which can be pushed down to the Aggregate later. For example, + * `SELECT max(a) FROM t GROUP BY b ORDER BY min(a)`. + * 4. Resolves the column to [[AttributeReference]] with the output of a descendant plan node. + * Spark will propagate the missing attributes from the descendant plan node to the Sort node. + * This is to allow users to ORDER BY columns that are not in the SELECT clause, which is + * widely supported in other SQL dialects. For example, `SELECT a FROM t ORDER BY b`. + * 5. If the order by expressions only have one single unresolved column named ALL, expanded it to + * include all columns in the SELECT list. This is to support SQL pattern like + * `SELECT col1, col2 FROM t ORDER BY ALL`. This should also support specifying asc/desc, and + * nulls first/last. + * 6. Resolves the column to outer references with the outer plan if we are resolving subquery + * expressions. + */ +object ResolveReferencesInSort extends SQLConfHelper with ColumnResolutionHelper { + + def apply(s: Sort): LogicalPlan = { + val resolvedNoOuter = s.order.map(resolveExpressionByPlanOutput(_, s.child)) + val resolvedWithAgg = resolvedNoOuter.map(resolveColWithAgg(_, s.child)) + val (missingAttrResolved, newChild) = resolveExprsAndAddMissingAttrs(resolvedWithAgg, s.child) + val orderByAllResolved = resolveOrderByAll( + s.global, newChild, missingAttrResolved.map(_.asInstanceOf[SortOrder])) Review Comment: ditoo -- 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. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
