risingwave_frontend/optimizer/rule/
except_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::{BoxedRule, Rule};
16use crate::optimizer::PlanRef;
17use crate::optimizer::plan_node::{LogicalExcept, PlanTreeNode};
18
19/// Different from `UnionMergeRule` and `IntersectMergeRule`, `ExceptMergeRule` can only merge its
20/// left most one input.
21pub struct ExceptMergeRule {}
22impl Rule for ExceptMergeRule {
23    fn apply(&self, plan: PlanRef) -> Option<PlanRef> {
24        let top_except: &LogicalExcept = plan.as_logical_except()?;
25        let top_all = top_except.all();
26        let top_except_inputs = top_except.inputs();
27        let (left_most_input, remain_vec) = top_except_inputs.split_at(1);
28
29        if let Some(bottom_except) = left_most_input[0].as_logical_except()
30            && bottom_except.all() == top_all
31        {
32            let mut new_inputs = vec![];
33            new_inputs.extend(bottom_except.inputs());
34            new_inputs.extend(remain_vec.iter().cloned());
35            Some(top_except.clone_with_inputs(&new_inputs))
36        } else {
37            None
38        }
39    }
40}
41
42impl ExceptMergeRule {
43    pub fn create() -> BoxedRule {
44        Box::new(ExceptMergeRule {})
45    }
46}
risingwave_frontend/optimizer/rule/except_merge_rule.rs

risingwave_frontend/optimizer/rule/
except_merge_rule.rs
