query/optimizer/
count_wildcard.rs

1// Copyright 2023 Greptime Team
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 datafusion::datasource::DefaultTableSource;
16use datafusion_common::tree_node::{
17    Transformed, TransformedResult, TreeNode, TreeNodeRecursion, TreeNodeVisitor,
18};
19use datafusion_common::{Column, Result as DataFusionResult, ScalarValue};
20use datafusion_expr::expr::{AggregateFunction, WindowFunction};
21use datafusion_expr::utils::COUNT_STAR_EXPANSION;
22use datafusion_expr::{Expr, LogicalPlan, WindowFunctionDefinition, col, lit};
23use datafusion_optimizer::AnalyzerRule;
24use datafusion_optimizer::utils::NamePreserver;
25use datafusion_sql::TableReference;
26use table::table::adapter::DfTableProviderAdapter;
27
28/// A replacement to DataFusion's [`CountWildcardRule`]. This rule
29/// would prefer to use TIME INDEX for counting wildcard as it's
30/// faster to read comparing to PRIMARY KEYs.
31///
32/// [`CountWildcardRule`]: datafusion::optimizer::analyzer::CountWildcardRule
33#[derive(Debug)]
34pub struct CountWildcardToTimeIndexRule;
35
36impl AnalyzerRule for CountWildcardToTimeIndexRule {
37    fn name(&self) -> &str {
38        "count_wildcard_to_time_index_rule"
39    }
40
41    fn analyze(
42        &self,
43        plan: LogicalPlan,
44        _config: &datafusion::config::ConfigOptions,
45    ) -> DataFusionResult<LogicalPlan> {
46        plan.transform_down_with_subqueries(&Self::analyze_internal)
47            .data()
48    }
49}
50
51impl CountWildcardToTimeIndexRule {
52    fn analyze_internal(plan: LogicalPlan) -> DataFusionResult<Transformed<LogicalPlan>> {
53        let name_preserver = NamePreserver::new(&plan);
54        let new_arg = if let Some(time_index) = Self::try_find_time_index_col(&plan) {
55            vec![col(time_index)]
56        } else {
57            vec![lit(COUNT_STAR_EXPANSION)]
58        };
59        plan.map_expressions(|expr| {
60            let original_name = name_preserver.save(&expr);
61            let transformed_expr = expr.transform_up(|expr| match expr {
62                Expr::WindowFunction(mut window_function)
63                    if Self::is_count_star_window_aggregate(&window_function) =>
64                {
65                    window_function.params.args.clone_from(&new_arg);
66                    Ok(Transformed::yes(Expr::WindowFunction(window_function)))
67                }
68                Expr::AggregateFunction(mut aggregate_function)
69                    if Self::is_count_star_aggregate(&aggregate_function) =>
70                {
71                    aggregate_function.params.args.clone_from(&new_arg);
72                    Ok(Transformed::yes(Expr::AggregateFunction(
73                        aggregate_function,
74                    )))
75                }
76                _ => Ok(Transformed::no(expr)),
77            })?;
78            Ok(transformed_expr.update_data(|data| original_name.restore(data)))
79        })
80    }
81
82    fn try_find_time_index_col(plan: &LogicalPlan) -> Option<Column> {
83        let mut finder = TimeIndexFinder::default();
84        // Safety: `TimeIndexFinder` won't throw error.
85        plan.visit(&mut finder).unwrap();
86        let col = finder.into_column();
87
88        // check if the time index is a valid column as for current plan
89        if let Some(col) = &col {
90            let mut is_valid = false;
91            // if more than one input, we give up and just use `count(1)`
92            if plan.inputs().len() > 1 {
93                return None;
94            }
95            for input in plan.inputs() {
96                if input.schema().has_column(col) {
97                    is_valid = true;
98                    break;
99                }
100            }
101            if !is_valid {
102                return None;
103            }
104        }
105
106        col
107    }
108}
109
110/// Utility functions from the original rule.
111impl CountWildcardToTimeIndexRule {
112    #[expect(deprecated)]
113    fn args_at_most_wildcard_or_literal_one(args: &[Expr]) -> bool {
114        match args {
115            [] => true,
116            [Expr::Literal(ScalarValue::Int64(Some(v)), _)] => *v == 1,
117            [Expr::Wildcard { .. }] => true,
118            _ => false,
119        }
120    }
121
122    fn is_count_star_aggregate(aggregate_function: &AggregateFunction) -> bool {
123        let args = &aggregate_function.params.args;
124        matches!(aggregate_function,
125            AggregateFunction {
126                func,
127                ..
128            } if func.name() == "count" && Self::args_at_most_wildcard_or_literal_one(args))
129    }
130
131    fn is_count_star_window_aggregate(window_function: &WindowFunction) -> bool {
132        let args = &window_function.params.args;
133        matches!(window_function.fun,
134                WindowFunctionDefinition::AggregateUDF(ref udaf)
135                    if udaf.name() == "count" && Self::args_at_most_wildcard_or_literal_one(args))
136    }
137}
138
139#[derive(Default)]
140struct TimeIndexFinder {
141    time_index_col: Option<String>,
142    table_alias: Option<TableReference>,
143}
144
145impl TreeNodeVisitor<'_> for TimeIndexFinder {
146    type Node = LogicalPlan;
147
148    fn f_down(&mut self, node: &Self::Node) -> DataFusionResult<TreeNodeRecursion> {
149        if let LogicalPlan::SubqueryAlias(subquery_alias) = node {
150            self.table_alias = Some(subquery_alias.alias.clone());
151        }
152
153        if let LogicalPlan::TableScan(table_scan) = &node
154            && let Some(source) = table_scan
155                .source
156                .as_any()
157                .downcast_ref::<DefaultTableSource>()
158            && let Some(adapter) = source
159                .table_provider
160                .as_any()
161                .downcast_ref::<DfTableProviderAdapter>()
162        {
163            let table_info = adapter.table().table_info();
164            self.table_alias
165                .get_or_insert(TableReference::bare(table_info.name.clone()));
166            self.time_index_col = table_info
167                .meta
168                .schema
169                .timestamp_column()
170                .map(|c| c.name.clone());
171
172            return Ok(TreeNodeRecursion::Stop);
173        }
174
175        if node.inputs().len() > 1 {
176            // if more than one input, we give up and just use `count(1)`
177            return Ok(TreeNodeRecursion::Stop);
178        }
179
180        Ok(TreeNodeRecursion::Continue)
181    }
182
183    fn f_up(&mut self, _node: &Self::Node) -> DataFusionResult<TreeNodeRecursion> {
184        Ok(TreeNodeRecursion::Stop)
185    }
186}
187
188impl TimeIndexFinder {
189    fn into_column(self) -> Option<Column> {
190        self.time_index_col
191            .map(|c| Column::new(self.table_alias, c))
192    }
193}
194
195#[cfg(test)]
196mod test {
197    use std::sync::Arc;
198
199    use datafusion::functions_aggregate::count::count_all;
200    use datafusion_expr::LogicalPlanBuilder;
201    use table::table::numbers::NumbersTable;
202
203    use super::*;
204
205    #[test]
206    fn uppercase_table_name() {
207        let numbers_table = NumbersTable::table_with_name(0, "AbCdE".to_string());
208        let table_source = Arc::new(DefaultTableSource::new(Arc::new(
209            DfTableProviderAdapter::new(numbers_table),
210        )));
211
212        let plan = LogicalPlanBuilder::scan_with_filters("t", table_source, None, vec![])
213            .unwrap()
214            .aggregate(Vec::<Expr>::new(), vec![count_all()])
215            .unwrap()
216            .alias(r#""FgHiJ""#)
217            .unwrap()
218            .build()
219            .unwrap();
220
221        let mut finder = TimeIndexFinder::default();
222        plan.visit(&mut finder).unwrap();
223
224        assert_eq!(finder.table_alias, Some(TableReference::bare("FgHiJ")));
225        assert!(finder.time_index_col.is_none());
226    }
227}
query/optimizer/count_wildcard.rs

query/optimizer/
count_wildcard.rs
