alamb commented on code in PR #11082: URL: https://github.com/apache/datafusion/pull/11082#discussion_r1650278660
########## datafusion/sql/src/unparser/rewrite.rs: ########## @@ -0,0 +1,96 @@ +// 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. + +use std::sync::Arc; + +use datafusion_common::{ + tree_node::{Transformed, TransformedResult, TreeNode, TreeNodeRewriter}, + Result, +}; +use datafusion_expr::{Expr, LogicalPlan, Sort}; + +/// Normalize the schema of a union plan to remove qualifiers from the schema fields. +pub(super) struct NormalizeUnionSchema {} + +impl NormalizeUnionSchema { + pub fn new() -> Self { + Self {} + } +} + +impl TreeNodeRewriter for NormalizeUnionSchema { + type Node = LogicalPlan; + + /// Invoked while traversing down the tree before any children are rewritten. + /// Default implementation returns the node as is and continues recursion. + fn f_down(&mut self, plan: LogicalPlan) -> Result<Transformed<LogicalPlan>> { + match plan { + LogicalPlan::Union(mut union) => { + let schema = match Arc::try_unwrap(union.schema) { + Ok(inner) => inner, + Err(schema) => (*schema).clone(), + }; + let schema = schema.strip_qualifiers(); + + union.schema = Arc::new(schema); + Ok(Transformed::yes(LogicalPlan::Union(union))) + } + LogicalPlan::Sort(sort) => { + if !matches!(&*sort.input, LogicalPlan::Union(_)) { + return Ok(Transformed::no(LogicalPlan::Sort(sort))); + } + + let mut sort_expr_rewriter = NormalizeSortExprForUnion::new(); + let sort_exprs: Vec<Expr> = sort + .expr + .into_iter() + .map(|expr| expr.rewrite(&mut sort_expr_rewriter).data()) + .collect::<Result<Vec<_>>>()?; Review Comment: You actually might be able to use `LogicalPlan::map_exprs` here instead of having to manually rewrite the sort_exprs too 🤔 https://github.com/apache/datafusion/blob/c7ac8b8221229b307bba434390ce1d19b7fb9358/datafusion/expr/src/logical_plan/tree_node.rs#L538C12-L538C27 ########## datafusion/sql/src/unparser/rewrite.rs: ########## @@ -0,0 +1,96 @@ +// 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. + +use std::sync::Arc; + +use datafusion_common::{ + tree_node::{Transformed, TransformedResult, TreeNode, TreeNodeRewriter}, + Result, +}; +use datafusion_expr::{Expr, LogicalPlan, Sort}; + +/// Normalize the schema of a union plan to remove qualifiers from the schema fields. +pub(super) struct NormalizeUnionSchema {} + +impl NormalizeUnionSchema { + pub fn new() -> Self { + Self {} + } +} + +impl TreeNodeRewriter for NormalizeUnionSchema { Review Comment: FYI because these two rewriters don't have state, you could also implement them using transform_up -- like ```rust let plan = plan.transform_up(|plan| { match plan { LogicalPlan::Union(mut union) => { let schema = match Arc::try_unwrap(union.schema) { Ok(inner) => inner, Err(schema) => (*schema).clone(), }; ... })?.data ``` ########## datafusion/sql/src/unparser/rewrite.rs: ########## @@ -0,0 +1,96 @@ +// 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. + +use std::sync::Arc; + +use datafusion_common::{ + tree_node::{Transformed, TransformedResult, TreeNode, TreeNodeRewriter}, + Result, +}; +use datafusion_expr::{Expr, LogicalPlan, Sort}; + +/// Normalize the schema of a union plan to remove qualifiers from the schema fields. +pub(super) struct NormalizeUnionSchema {} + +impl NormalizeUnionSchema { + pub fn new() -> Self { + Self {} + } +} + +impl TreeNodeRewriter for NormalizeUnionSchema { + type Node = LogicalPlan; + + /// Invoked while traversing down the tree before any children are rewritten. + /// Default implementation returns the node as is and continues recursion. + fn f_down(&mut self, plan: LogicalPlan) -> Result<Transformed<LogicalPlan>> { + match plan { + LogicalPlan::Union(mut union) => { + let schema = match Arc::try_unwrap(union.schema) { + Ok(inner) => inner, + Err(schema) => (*schema).clone(), + }; + let schema = schema.strip_qualifiers(); + + union.schema = Arc::new(schema); + Ok(Transformed::yes(LogicalPlan::Union(union))) + } + LogicalPlan::Sort(sort) => { + if !matches!(&*sort.input, LogicalPlan::Union(_)) { + return Ok(Transformed::no(LogicalPlan::Sort(sort))); + } + + let mut sort_expr_rewriter = NormalizeSortExprForUnion::new(); + let sort_exprs: Vec<Expr> = sort + .expr + .into_iter() + .map(|expr| expr.rewrite(&mut sort_expr_rewriter).data()) + .collect::<Result<Vec<_>>>()?; Review Comment: If you want, you could avoid the rewriter here too via ```rust let sort_exprs: Vec<Expr> = sort .expr .into_iter() .map_until_stop_and_collect(|expr| { expr.transform_up(|expr| { if let Expr::Column(mut col) = expr { col.relation = None; Ok(Transformed::yes(Expr::Column(col))) } else { Ok(Transformed::no(expr)) } }) })?.data; ``` However, I will admit the rewriter keeps the logic nicely separated which is nice ########## datafusion/sql/src/unparser/rewrite.rs: ########## @@ -0,0 +1,96 @@ +// 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. + +use std::sync::Arc; + +use datafusion_common::{ + tree_node::{Transformed, TransformedResult, TreeNode, TreeNodeRewriter}, + Result, +}; +use datafusion_expr::{Expr, LogicalPlan, Sort}; + +/// Normalize the schema of a union plan to remove qualifiers from the schema fields. +pub(super) struct NormalizeUnionSchema {} + +impl NormalizeUnionSchema { + pub fn new() -> Self { + Self {} + } +} + +impl TreeNodeRewriter for NormalizeUnionSchema { + type Node = LogicalPlan; + + /// Invoked while traversing down the tree before any children are rewritten. + /// Default implementation returns the node as is and continues recursion. + fn f_down(&mut self, plan: LogicalPlan) -> Result<Transformed<LogicalPlan>> { + match plan { + LogicalPlan::Union(mut union) => { + let schema = match Arc::try_unwrap(union.schema) { + Ok(inner) => inner, + Err(schema) => (*schema).clone(), + }; + let schema = schema.strip_qualifiers(); + + union.schema = Arc::new(schema); + Ok(Transformed::yes(LogicalPlan::Union(union))) + } + LogicalPlan::Sort(sort) => { Review Comment: It might be worth documenting here why this very special pattern is verified -- specifically for the unparser -- This is an automated message from the Apache Git Service. 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