/Users/andrewlamb/Software/datafusion/datafusion/physical-plan/src/empty.rs
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1 | | // Licensed to the Apache Software Foundation (ASF) under one |
2 | | // or more contributor license agreements. See the NOTICE file |
3 | | // distributed with this work for additional information |
4 | | // regarding copyright ownership. The ASF licenses this file |
5 | | // to you under the Apache License, Version 2.0 (the |
6 | | // "License"); you may not use this file except in compliance |
7 | | // with the License. You may obtain a copy of the License at |
8 | | // |
9 | | // http://www.apache.org/licenses/LICENSE-2.0 |
10 | | // |
11 | | // Unless required by applicable law or agreed to in writing, |
12 | | // software distributed under the License is distributed on an |
13 | | // "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
14 | | // KIND, either express or implied. See the License for the |
15 | | // specific language governing permissions and limitations |
16 | | // under the License. |
17 | | |
18 | | //! EmptyRelation with produce_one_row=false execution plan |
19 | | |
20 | | use std::any::Any; |
21 | | use std::sync::Arc; |
22 | | |
23 | | use super::{ |
24 | | common, DisplayAs, ExecutionMode, PlanProperties, SendableRecordBatchStream, |
25 | | Statistics, |
26 | | }; |
27 | | use crate::{memory::MemoryStream, DisplayFormatType, ExecutionPlan, Partitioning}; |
28 | | |
29 | | use arrow::datatypes::SchemaRef; |
30 | | use arrow::record_batch::RecordBatch; |
31 | | use datafusion_common::{internal_err, Result}; |
32 | | use datafusion_execution::TaskContext; |
33 | | use datafusion_physical_expr::EquivalenceProperties; |
34 | | |
35 | | use log::trace; |
36 | | |
37 | | /// Execution plan for empty relation with produce_one_row=false |
38 | | #[derive(Debug)] |
39 | | pub struct EmptyExec { |
40 | | /// The schema for the produced row |
41 | | schema: SchemaRef, |
42 | | /// Number of partitions |
43 | | partitions: usize, |
44 | | cache: PlanProperties, |
45 | | } |
46 | | |
47 | | impl EmptyExec { |
48 | | /// Create a new EmptyExec |
49 | 4 | pub fn new(schema: SchemaRef) -> Self { |
50 | 4 | let cache = Self::compute_properties(Arc::clone(&schema), 1); |
51 | 4 | EmptyExec { |
52 | 4 | schema, |
53 | 4 | partitions: 1, |
54 | 4 | cache, |
55 | 4 | } |
56 | 4 | } |
57 | | |
58 | | /// Create a new EmptyExec with specified partition number |
59 | 0 | pub fn with_partitions(mut self, partitions: usize) -> Self { |
60 | 0 | self.partitions = partitions; |
61 | 0 | // Changing partitions may invalidate output partitioning, so update it: |
62 | 0 | let output_partitioning = Self::output_partitioning_helper(self.partitions); |
63 | 0 | self.cache = self.cache.with_partitioning(output_partitioning); |
64 | 0 | self |
65 | 0 | } |
66 | | |
67 | 3 | fn data(&self) -> Result<Vec<RecordBatch>> { |
68 | 3 | Ok(vec![]) |
69 | 3 | } |
70 | | |
71 | 4 | fn output_partitioning_helper(n_partitions: usize) -> Partitioning { |
72 | 4 | Partitioning::UnknownPartitioning(n_partitions) |
73 | 4 | } |
74 | | |
75 | | /// This function creates the cache object that stores the plan properties such as schema, equivalence properties, ordering, partitioning, etc. |
76 | 4 | fn compute_properties(schema: SchemaRef, n_partitions: usize) -> PlanProperties { |
77 | 4 | let eq_properties = EquivalenceProperties::new(schema); |
78 | 4 | let output_partitioning = Self::output_partitioning_helper(n_partitions); |
79 | 4 | PlanProperties::new( |
80 | 4 | eq_properties, |
81 | 4 | // Output Partitioning |
82 | 4 | output_partitioning, |
83 | 4 | // Execution Mode |
84 | 4 | ExecutionMode::Bounded, |
85 | 4 | ) |
86 | 4 | } |
87 | | } |
88 | | |
89 | | impl DisplayAs for EmptyExec { |
90 | 0 | fn fmt_as( |
91 | 0 | &self, |
92 | 0 | t: DisplayFormatType, |
93 | 0 | f: &mut std::fmt::Formatter, |
94 | 0 | ) -> std::fmt::Result { |
95 | 0 | match t { |
96 | | DisplayFormatType::Default | DisplayFormatType::Verbose => { |
97 | 0 | write!(f, "EmptyExec") |
98 | 0 | } |
99 | 0 | } |
100 | 0 | } |
101 | | } |
102 | | |
103 | | impl ExecutionPlan for EmptyExec { |
104 | 0 | fn name(&self) -> &'static str { |
105 | 0 | "EmptyExec" |
106 | 0 | } |
107 | | |
108 | | /// Return a reference to Any that can be used for downcasting |
109 | 0 | fn as_any(&self) -> &dyn Any { |
110 | 0 | self |
111 | 0 | } |
112 | | |
113 | 12 | fn properties(&self) -> &PlanProperties { |
114 | 12 | &self.cache |
115 | 12 | } |
116 | | |
117 | 2 | fn children(&self) -> Vec<&Arc<dyn ExecutionPlan>> { |
118 | 2 | vec![] |
119 | 2 | } |
120 | | |
121 | 1 | fn with_new_children( |
122 | 1 | self: Arc<Self>, |
123 | 1 | _: Vec<Arc<dyn ExecutionPlan>>, |
124 | 1 | ) -> Result<Arc<dyn ExecutionPlan>> { |
125 | 1 | Ok(self) |
126 | 1 | } |
127 | | |
128 | 3 | fn execute( |
129 | 3 | &self, |
130 | 3 | partition: usize, |
131 | 3 | context: Arc<TaskContext>, |
132 | 3 | ) -> Result<SendableRecordBatchStream> { |
133 | 3 | trace!("Start EmptyExec::execute for partition {} of context session_id {} and task_id {:?}", partition, context.session_id(), context.task_id()0 ); |
134 | | |
135 | 3 | if partition >= self.partitions { |
136 | 2 | return internal_err!( |
137 | 2 | "EmptyExec invalid partition {} (expected less than {})", |
138 | 2 | partition, |
139 | 2 | self.partitions |
140 | 2 | ); |
141 | 1 | } |
142 | 1 | |
143 | 1 | Ok(Box::pin(MemoryStream::try_new( |
144 | 1 | self.data()?0 , |
145 | 1 | Arc::clone(&self.schema), |
146 | 1 | None, |
147 | 0 | )?)) |
148 | 3 | } |
149 | | |
150 | 2 | fn statistics(&self) -> Result<Statistics> { |
151 | 2 | let batch = self |
152 | 2 | .data() |
153 | 2 | .expect("Create empty RecordBatch should not fail"); |
154 | 2 | Ok(common::compute_record_batch_statistics( |
155 | 2 | &[batch], |
156 | 2 | &self.schema, |
157 | 2 | None, |
158 | 2 | )) |
159 | 2 | } |
160 | | } |
161 | | |
162 | | #[cfg(test)] |
163 | | mod tests { |
164 | | use super::*; |
165 | | use crate::test; |
166 | | use crate::with_new_children_if_necessary; |
167 | | |
168 | | #[tokio::test] |
169 | 1 | async fn empty() -> Result<()> { |
170 | 1 | let task_ctx = Arc::new(TaskContext::default()); |
171 | 1 | let schema = test::aggr_test_schema(); |
172 | 1 | |
173 | 1 | let empty = EmptyExec::new(Arc::clone(&schema)); |
174 | 1 | assert_eq!(empty.schema(), schema); |
175 | 1 | |
176 | 1 | // we should have no results |
177 | 1 | let iter = empty.execute(0, task_ctx)?0 ; |
178 | 1 | let batches = common::collect(iter).await0 ?0 ; |
179 | 1 | assert!(batches.is_empty()); |
180 | 1 | |
181 | 1 | Ok(()) |
182 | 1 | } |
183 | | |
184 | | #[test] |
185 | 1 | fn with_new_children() -> Result<()> { |
186 | 1 | let schema = test::aggr_test_schema(); |
187 | 1 | let empty = Arc::new(EmptyExec::new(Arc::clone(&schema))); |
188 | | |
189 | 1 | let empty2 = with_new_children_if_necessary( |
190 | 1 | Arc::clone(&empty) as Arc<dyn ExecutionPlan>, |
191 | 1 | vec![], |
192 | 1 | )?0 ; |
193 | 1 | assert_eq!(empty.schema(), empty2.schema()); |
194 | | |
195 | 1 | let too_many_kids = vec![empty2]; |
196 | 1 | assert!( |
197 | 1 | with_new_children_if_necessary(empty, too_many_kids).is_err(), |
198 | 0 | "expected error when providing list of kids" |
199 | | ); |
200 | 1 | Ok(()) |
201 | 1 | } |
202 | | |
203 | | #[tokio::test] |
204 | 1 | async fn invalid_execute() -> Result<()> { |
205 | 1 | let task_ctx = Arc::new(TaskContext::default()); |
206 | 1 | let schema = test::aggr_test_schema(); |
207 | 1 | let empty = EmptyExec::new(schema); |
208 | 1 | |
209 | 1 | // ask for the wrong partition |
210 | 1 | assert!(empty.execute(1, Arc::clone(&task_ctx)).is_err()); |
211 | 1 | assert!(empty.execute(20, task_ctx).is_err()); |
212 | 1 | Ok(()) |
213 | 1 | } |
214 | | } |