risingwave_frontend/optimizer/plan_node/generic/
expand.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 pretty_xmlish::{Pretty, Str, XmlNode};
17use risingwave_common::catalog::{Field, FieldDisplay, Schema};
18use risingwave_common::types::DataType;
19use risingwave_common::util::column_index_mapping::ColIndexMapping;
20
21use super::{DistillUnit, GenericPlanNode, GenericPlanRef};
22use crate::optimizer::optimizer_context::OptimizerContextRef;
23use crate::optimizer::plan_node::utils::childless_record;
24use crate::optimizer::property::FunctionalDependencySet;
25
26/// [`Expand`] expand one row multiple times according to `column_subsets` and also keep
27/// original columns of input. It can be used to implement distinct aggregation and group set.
28///
29/// This is the schema of `Expand`:
30/// | expanded columns(i.e. some columns are set to null) | original columns of input | flag |.
31///
32/// Aggregates use expanded columns as their arguments and original columns for their filter. `flag`
33/// is used to distinguish between different `subset`s in `column_subsets`.
34#[derive(Debug, Clone, PartialEq, Eq, Hash)]
35pub struct Expand<PlanRef> {
36    // `column_subsets` has many `subset`s which specifies the columns that need to be
37    // reserved and other columns will be filled with NULL.
38    pub column_subsets: Vec<Vec<usize>>,
39    pub input: PlanRef,
40}
41
42impl<PlanRef: GenericPlanRef> Expand<PlanRef> {
43    pub fn output_len(&self) -> usize {
44        self.input.schema().len() * 2 + 1
45    }
46
47    fn flag_index(&self) -> usize {
48        self.output_len() - 1
49    }
50
51    pub fn clone_with_input<OtherPlanRef>(&self, input: OtherPlanRef) -> Expand<OtherPlanRef> {
52        Expand {
53            column_subsets: self.column_subsets.clone(),
54            input,
55        }
56    }
57}
58
59impl<PlanRef: GenericPlanRef> GenericPlanNode for Expand<PlanRef> {
60    fn schema(&self) -> Schema {
61        let mut fields = self
62            .input
63            .schema()
64            .fields()
65            .iter()
66            .map(|f| Field::with_name(f.data_type(), format!("{}_expanded", f.name)))
67            .collect::<Vec<_>>();
68        fields.extend(self.input.schema().fields().iter().cloned());
69        fields.push(Field::with_name(DataType::Int64, "flag"));
70        Schema::new(fields)
71    }
72
73    fn stream_key(&self) -> Option<Vec<usize>> {
74        let input_schema_len = self.input.schema().len();
75        let mut pk_indices = self
76            .input
77            .stream_key()?
78            .iter()
79            .map(|&pk| pk + input_schema_len)
80            .collect_vec();
81        // The last column should be the flag.
82        pk_indices.push(input_schema_len * 2);
83        Some(pk_indices)
84    }
85
86    fn ctx(&self) -> OptimizerContextRef {
87        self.input.ctx()
88    }
89
90    fn functional_dependency(&self) -> FunctionalDependencySet {
91        let input_fd = self
92            .input
93            .functional_dependency()
94            .clone()
95            .into_dependencies();
96        let output_len = self.output_len();
97        let flag_index = self.flag_index();
98
99        self.input
100            .functional_dependency()
101            .as_dependencies()
102            .iter()
103            .map(|_input_fd| {})
104            .collect_vec();
105
106        let mut current_fd = FunctionalDependencySet::new(output_len);
107        for mut fd in input_fd {
108            fd.grow(output_len);
109            fd.set_from(flag_index, true);
110            current_fd.add_functional_dependency(fd);
111        }
112        current_fd
113    }
114}
115
116impl<PlanRef: GenericPlanRef> DistillUnit for Expand<PlanRef> {
117    fn distill_with_name<'a>(&self, name: impl Into<Str<'a>>) -> XmlNode<'a> {
118        childless_record(name, vec![("column_subsets", self.column_subsets_pretty())])
119    }
120}
121
122impl<PlanRef: GenericPlanRef> Expand<PlanRef> {
123    fn column_subsets_pretty<'a>(&self) -> Pretty<'a> {
124        Pretty::Array(
125            self.column_subsets
126                .iter()
127                .map(|subset| {
128                    subset
129                        .iter()
130                        .map(|&i| FieldDisplay(self.input.schema().fields.get(i).unwrap()))
131                        .map(|d| Pretty::display(&d))
132                        .collect()
133                })
134                .map(Pretty::Array)
135                .collect(),
136        )
137    }
138
139    pub fn i2o_col_mapping(&self) -> ColIndexMapping {
140        let input_len = self.input.schema().len();
141        let map = (0..input_len)
142            .map(|source| Some(source + input_len))
143            .collect_vec();
144        ColIndexMapping::new(map, self.output_len())
145    }
146
147    pub fn o2i_col_mapping(&self) -> ColIndexMapping {
148        self.i2o_col_mapping()
149            .inverse()
150            .expect("must be invertible")
151    }
152
153    pub fn decompose(self) -> (PlanRef, Vec<Vec<usize>>) {
154        (self.input, self.column_subsets)
155    }
156}
risingwave_frontend/optimizer/plan_node/generic/expand.rs

risingwave_frontend/optimizer/plan_node/generic/
expand.rs
