paimon 0.1.0

The rust implementation of Apache Paimon
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151

// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License.  You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.

//! Schema evolution utilities for mapping between table schema and data file schema.
//!
//! Reference: [org.apache.paimon.schema.SchemaEvolutionUtil](https://github.com/apache/paimon/blob/release-1.3/paimon-core/src/main/java/org/apache/paimon/schema/SchemaEvolutionUtil.java)

use crate::spec::DataField;
use std::collections::HashMap;

/// Sentinel value indicating a field does not exist in the data schema.
pub const NULL_FIELD_INDEX: i32 = -1;

/// Create index mapping from table fields to underlying data fields using field IDs.
///
/// For example, the table and data fields are as follows:
/// - table fields: `1->c, 6->b, 3->a`
/// - data fields: `1->a, 3->c`
///
/// We get the index mapping `[0, -1, 1]`, where:
/// - `0` is the index of table field `1->c` in data fields
/// - `-1` means field `6->b` does not exist in data fields
/// - `1` is the index of table field `3->a` in data fields
///
/// Returns `None` if the mapping is identity (no evolution needed).
///
/// Reference: [SchemaEvolutionUtil.createIndexMapping](https://github.com/apache/paimon/blob/release-1.3/paimon-core/src/main/java/org/apache/paimon/schema/SchemaEvolutionUtil.java)
pub fn create_index_mapping(
    table_fields: &[DataField],
    data_fields: &[DataField],
) -> Option<Vec<i32>> {
    let mut field_id_to_index: HashMap<i32, i32> = HashMap::with_capacity(data_fields.len());
    for (i, field) in data_fields.iter().enumerate() {
        field_id_to_index.insert(field.id(), i as i32);
    }

    let mut index_mapping = Vec::with_capacity(table_fields.len());
    for field in table_fields {
        let data_index = field_id_to_index
            .get(&field.id())
            .copied()
            .unwrap_or(NULL_FIELD_INDEX);
        index_mapping.push(data_index);
    }

    // Check if mapping is identity (no evolution needed).
    let is_identity = index_mapping.len() == data_fields.len()
        && index_mapping
            .iter()
            .enumerate()
            .all(|(i, &idx)| idx == i as i32);

    if is_identity {
        None
    } else {
        Some(index_mapping)
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::spec::{DataType, IntType, VarCharType};

    fn field(id: i32, name: &str) -> DataField {
        DataField::new(id, name.to_string(), DataType::Int(IntType::new()))
    }

    #[test]
    fn test_identity_mapping() {
        let table_fields = vec![field(0, "a"), field(1, "b"), field(2, "c")];
        let data_fields = vec![field(0, "a"), field(1, "b"), field(2, "c")];
        assert_eq!(create_index_mapping(&table_fields, &data_fields), None);
    }

    #[test]
    fn test_added_column() {
        // Table has 3 fields, data file only has the first 2
        let table_fields = vec![field(0, "a"), field(1, "b"), field(2, "c")];
        let data_fields = vec![field(0, "a"), field(1, "b")];
        assert_eq!(
            create_index_mapping(&table_fields, &data_fields),
            Some(vec![0, 1, -1])
        );
    }

    #[test]
    fn test_reordered_fields() {
        let table_fields = vec![field(1, "c"), field(6, "b"), field(3, "a")];
        let data_fields = vec![field(1, "a"), field(3, "c")];
        assert_eq!(
            create_index_mapping(&table_fields, &data_fields),
            Some(vec![0, -1, 1])
        );
    }

    #[test]
    fn test_renamed_column() {
        // Field ID stays the same even if name changed
        let table_fields = vec![field(0, "id"), field(1, "new_name")];
        let data_fields = vec![field(0, "id"), field(1, "old_name")];
        // Identity mapping since field IDs match positionally
        assert_eq!(create_index_mapping(&table_fields, &data_fields), None);
    }

    #[test]
    fn test_empty_data_fields() {
        let table_fields = vec![field(0, "a"), field(1, "b")];
        let data_fields: Vec<DataField> = vec![];
        assert_eq!(
            create_index_mapping(&table_fields, &data_fields),
            Some(vec![-1, -1])
        );
    }

    #[test]
    fn test_type_promotion_same_mapping() {
        // Type promotion doesn't affect index mapping — only field IDs matter
        let table_fields = vec![
            DataField::new(0, "id".to_string(), DataType::Int(IntType::new())),
            DataField::new(
                1,
                "name".to_string(),
                DataType::VarChar(VarCharType::string_type()),
            ),
        ];
        let data_fields = vec![
            DataField::new(0, "id".to_string(), DataType::Int(IntType::new())),
            DataField::new(
                1,
                "name".to_string(),
                DataType::VarChar(VarCharType::string_type()),
            ),
        ];
        assert_eq!(create_index_mapping(&table_fields, &data_fields), None);
    }
}