risingwave_frontend/optimizer/rule/
project_merge_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};
17use crate::expr::{ExprImpl, ExprRewriter, ExprVisitor};
18use crate::optimizer::plan_expr_visitor::InputRefCounter;
19use crate::utils::Substitute;
20
21/// Merge contiguous [`LogicalProject`] nodes.
22pub struct ProjectMergeRule {}
23impl Rule for ProjectMergeRule {
24    fn apply(&self, plan: PlanRef) -> Option<PlanRef> {
25        let outer_project: &LogicalProject = plan.as_logical_project()?;
26        let input = outer_project.input();
27        let inner_project: &LogicalProject = input.as_logical_project()?;
28
29        let mut input_ref_counter = InputRefCounter::default();
30        for expr in outer_project.exprs() {
31            input_ref_counter.visit_expr(expr);
32        }
33        // bail out if it is a project generated by `CommonSubExprExtractRule`.
34        for (index, count) in &input_ref_counter.counter {
35            if *count > 1 && matches!(inner_project.exprs()[*index], ExprImpl::FunctionCall(_)) {
36                return None;
37            }
38        }
39
40        let mut subst = Substitute {
41            mapping: inner_project.exprs().clone(),
42        };
43        let exprs = outer_project
44            .exprs()
45            .iter()
46            .cloned()
47            .map(|expr| subst.rewrite_expr(expr))
48            .collect();
49        Some(LogicalProject::new(inner_project.input(), exprs).into())
50    }
51}
52
53impl ProjectMergeRule {
54    pub fn create() -> BoxedRule {
55        Box::new(ProjectMergeRule {})
56    }
57}
risingwave_frontend/optimizer/rule/project_merge_rule.rs

risingwave_frontend/optimizer/rule/
project_merge_rule.rs
