risingwave_frontend/optimizer/rule/
project_eliminate_rule.rs

1// Copyright 2025 RisingWave Labs
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7//     http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15use super::super::plan_node::*;
16use super::{BoxedRule, Rule};
17
18/// Eliminate useless (identity) [`LogicalProject`] nodes.
19pub struct ProjectEliminateRule {}
20impl Rule for ProjectEliminateRule {
21    fn apply(&self, plan: PlanRef) -> Option<PlanRef> {
22        let project = plan.as_logical_project()?;
23        if project.is_identity() {
24            Some(project.input())
25        } else {
26            None
27        }
28    }
29}
30
31impl ProjectEliminateRule {
32    pub fn create() -> BoxedRule {
33        Box::new(ProjectEliminateRule {})
34    }
35}