/Users/andrewlamb/Software/datafusion/datafusion/expr/src/logical_plan/statement.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 | | use datafusion_common::DFSchemaRef; |
19 | | use std::cmp::Ordering; |
20 | | use std::fmt::{self, Display}; |
21 | | |
22 | | /// Various types of Statements. |
23 | | /// |
24 | | /// # Transactions: |
25 | | /// |
26 | | /// While DataFusion does not offer support transactions, it provides |
27 | | /// [`LogicalPlan`](crate::LogicalPlan) support to assist building |
28 | | /// database systems using DataFusion |
29 | | #[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Hash)] |
30 | | pub enum Statement { |
31 | | // Begin a transaction |
32 | | TransactionStart(TransactionStart), |
33 | | // Commit or rollback a transaction |
34 | | TransactionEnd(TransactionEnd), |
35 | | /// Set a Variable |
36 | | SetVariable(SetVariable), |
37 | | } |
38 | | |
39 | | impl Statement { |
40 | | /// Get a reference to the logical plan's schema |
41 | 0 | pub fn schema(&self) -> &DFSchemaRef { |
42 | 0 | match self { |
43 | 0 | Statement::TransactionStart(TransactionStart { schema, .. }) => schema, |
44 | 0 | Statement::TransactionEnd(TransactionEnd { schema, .. }) => schema, |
45 | 0 | Statement::SetVariable(SetVariable { schema, .. }) => schema, |
46 | | } |
47 | 0 | } |
48 | | |
49 | | /// Return a descriptive string describing the type of this |
50 | | /// [`Statement`] |
51 | 0 | pub fn name(&self) -> &str { |
52 | 0 | match self { |
53 | 0 | Statement::TransactionStart(_) => "TransactionStart", |
54 | 0 | Statement::TransactionEnd(_) => "TransactionEnd", |
55 | 0 | Statement::SetVariable(_) => "SetVariable", |
56 | | } |
57 | 0 | } |
58 | | |
59 | | /// Return a `format`able structure with the a human readable |
60 | | /// description of this LogicalPlan node per node, not including |
61 | | /// children. |
62 | | /// |
63 | | /// See [crate::LogicalPlan::display] for an example |
64 | 0 | pub fn display(&self) -> impl fmt::Display + '_ { |
65 | | struct Wrapper<'a>(&'a Statement); |
66 | | impl<'a> Display for Wrapper<'a> { |
67 | 0 | fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { |
68 | 0 | match self.0 { |
69 | | Statement::TransactionStart(TransactionStart { |
70 | 0 | access_mode, |
71 | 0 | isolation_level, |
72 | 0 | .. |
73 | 0 | }) => { |
74 | 0 | write!(f, "TransactionStart: {access_mode:?} {isolation_level:?}") |
75 | | } |
76 | | Statement::TransactionEnd(TransactionEnd { |
77 | 0 | conclusion, |
78 | 0 | chain, |
79 | 0 | .. |
80 | 0 | }) => { |
81 | 0 | write!(f, "TransactionEnd: {conclusion:?} chain:={chain}") |
82 | | } |
83 | | Statement::SetVariable(SetVariable { |
84 | 0 | variable, value, .. |
85 | 0 | }) => { |
86 | 0 | write!(f, "SetVariable: set {variable:?} to {value:?}") |
87 | | } |
88 | | } |
89 | 0 | } |
90 | | } |
91 | 0 | Wrapper(self) |
92 | 0 | } |
93 | | } |
94 | | |
95 | | /// Indicates if a transaction was committed or aborted |
96 | | #[derive(Clone, PartialEq, Eq, PartialOrd, Hash, Debug)] |
97 | | pub enum TransactionConclusion { |
98 | | Commit, |
99 | | Rollback, |
100 | | } |
101 | | |
102 | | /// Indicates if this transaction is allowed to write |
103 | | #[derive(Clone, PartialEq, Eq, PartialOrd, Hash, Debug)] |
104 | | pub enum TransactionAccessMode { |
105 | | ReadOnly, |
106 | | ReadWrite, |
107 | | } |
108 | | |
109 | | /// Indicates ANSI transaction isolation level |
110 | | #[derive(Clone, PartialEq, Eq, PartialOrd, Hash, Debug)] |
111 | | pub enum TransactionIsolationLevel { |
112 | | ReadUncommitted, |
113 | | ReadCommitted, |
114 | | RepeatableRead, |
115 | | Serializable, |
116 | | } |
117 | | |
118 | | /// Indicator that the following statements should be committed or rolled back atomically |
119 | | #[derive(Debug, Clone, PartialEq, Eq, Hash)] |
120 | | pub struct TransactionStart { |
121 | | /// indicates if transaction is allowed to write |
122 | | pub access_mode: TransactionAccessMode, |
123 | | // indicates ANSI isolation level |
124 | | pub isolation_level: TransactionIsolationLevel, |
125 | | /// Empty schema |
126 | | pub schema: DFSchemaRef, |
127 | | } |
128 | | |
129 | | // Manual implementation needed because of `schema` field. Comparison excludes this field. |
130 | | impl PartialOrd for TransactionStart { |
131 | 0 | fn partial_cmp(&self, other: &Self) -> Option<Ordering> { |
132 | 0 | match self.access_mode.partial_cmp(&other.access_mode) { |
133 | | Some(Ordering::Equal) => { |
134 | 0 | self.isolation_level.partial_cmp(&other.isolation_level) |
135 | | } |
136 | 0 | cmp => cmp, |
137 | | } |
138 | 0 | } |
139 | | } |
140 | | |
141 | | /// Indicator that any current transaction should be terminated |
142 | | #[derive(Debug, Clone, PartialEq, Eq, Hash)] |
143 | | pub struct TransactionEnd { |
144 | | /// whether the transaction committed or aborted |
145 | | pub conclusion: TransactionConclusion, |
146 | | /// if specified a new transaction is immediately started with same characteristics |
147 | | pub chain: bool, |
148 | | /// Empty schema |
149 | | pub schema: DFSchemaRef, |
150 | | } |
151 | | |
152 | | // Manual implementation needed because of `schema` field. Comparison excludes this field. |
153 | | impl PartialOrd for TransactionEnd { |
154 | 0 | fn partial_cmp(&self, other: &Self) -> Option<Ordering> { |
155 | 0 | match self.conclusion.partial_cmp(&other.conclusion) { |
156 | 0 | Some(Ordering::Equal) => self.chain.partial_cmp(&other.chain), |
157 | 0 | cmp => cmp, |
158 | | } |
159 | 0 | } |
160 | | } |
161 | | |
162 | | /// Set a Variable's value -- value in |
163 | | /// [`ConfigOptions`](datafusion_common::config::ConfigOptions) |
164 | | #[derive(Debug, Clone, PartialEq, Eq, Hash)] |
165 | | pub struct SetVariable { |
166 | | /// The variable name |
167 | | pub variable: String, |
168 | | /// The value to set |
169 | | pub value: String, |
170 | | /// Dummy schema |
171 | | pub schema: DFSchemaRef, |
172 | | } |
173 | | |
174 | | // Manual implementation needed because of `schema` field. Comparison excludes this field. |
175 | | impl PartialOrd for SetVariable { |
176 | 0 | fn partial_cmp(&self, other: &Self) -> Option<Ordering> { |
177 | 0 | match self.variable.partial_cmp(&other.value) { |
178 | 0 | Some(Ordering::Equal) => self.value.partial_cmp(&other.value), |
179 | 0 | cmp => cmp, |
180 | | } |
181 | 0 | } |
182 | | } |