risingwave_frontend/optimizer/rule/
apply_topn_transpose_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 itertools::Itertools;
16use risingwave_pb::plan_common::JoinType;
17
18use super::{BoxedRule, Rule};
19use crate::optimizer::PlanRef;
20use crate::optimizer::plan_node::{LogicalApply, LogicalFilter, LogicalTopN};
21use crate::utils::Condition;
22
23/// Transpose `LogicalApply` and `LogicalTopN`.
24///
25/// Before:
26///
27/// ```text
28///     LogicalApply
29///    /            \
30///  Domain      LogicalTopN
31///                  |
32///                Input
33/// ```
34///
35/// After:
36///
37/// ```text
38///      LogicalTopN
39///          |
40///     LogicalApply
41///    /            \
42///  Domain        Input
43/// ```
44pub struct ApplyTopNTransposeRule {}
45impl Rule for ApplyTopNTransposeRule {
46    fn apply(&self, plan: PlanRef) -> Option<PlanRef> {
47        let apply: &LogicalApply = plan.as_logical_apply()?;
48        let (left, right, on, join_type, correlated_id, correlated_indices, max_one_row) =
49            apply.clone().decompose();
50        assert_eq!(join_type, JoinType::Inner);
51        let topn: &LogicalTopN = right.as_logical_top_n()?;
52        let (topn_input, limit, offset, with_ties, mut order, mut group_key) =
53            topn.clone().decompose();
54
55        let apply_left_len = left.schema().len();
56
57        if max_one_row {
58            return None;
59        }
60
61        let new_apply = LogicalApply::create(
62            left,
63            topn_input,
64            JoinType::Inner,
65            Condition::true_cond(),
66            correlated_id,
67            correlated_indices,
68            false,
69        );
70
71        let new_topn = {
72            // shift index of topn's `InputRef` with `apply_left_len`.
73            order
74                .column_orders
75                .iter_mut()
76                .for_each(|ord| ord.column_index += apply_left_len);
77            group_key.iter_mut().for_each(|idx| *idx += apply_left_len);
78            let new_group_key = (0..apply_left_len).chain(group_key).collect_vec();
79            LogicalTopN::new(new_apply, limit, offset, with_ties, order, new_group_key)
80        };
81
82        let filter = LogicalFilter::create(new_topn.into(), on);
83        Some(filter)
84    }
85}
86
87impl ApplyTopNTransposeRule {
88    pub fn create() -> BoxedRule {
89        Box::new(ApplyTopNTransposeRule {})
90    }
91}
risingwave_frontend/optimizer/rule/apply_topn_transpose_rule.rs

risingwave_frontend/optimizer/rule/
apply_topn_transpose_rule.rs
