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
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191

// 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.

//! Bin packing utilities for splitting data files into reasonably-sized groups.
//!
//! Reference: [BinPacking](https://github.com/apache/paimon/blob/release-1.3/paimon-common/src/main/java/org/apache/paimon/utils/BinPacking.java)

use crate::spec::DataFileMeta;
use std::cmp;

/// Greedy order-preserving bin packing.
///
/// Groups items into bins where each bin's total weight does not exceed `target_weight`.
/// Items are never reordered across bins. A single item larger than `target_weight`
/// will become its own bin.
///
/// Reference: [BinPacking.packForOrdered](https://github.com/apache/paimon/blob/release-1.3/paimon-common/src/main/java/org/apache/paimon/utils/BinPacking.java)
pub fn pack_for_ordered<T>(
    items: Vec<T>,
    weight_func: impl Fn(&T) -> i64,
    target_weight: i64,
) -> Vec<Vec<T>> {
    let mut packed: Vec<Vec<T>> = Vec::new();
    let mut bin_items: Vec<T> = Vec::new();
    let mut bin_weight: i64 = 0;

    for item in items {
        let weight = weight_func(&item);
        if bin_weight + weight > target_weight && !bin_items.is_empty() {
            packed.push(bin_items);
            bin_items = Vec::new();
            bin_weight = 0;
        }
        bin_weight += weight;
        bin_items.push(item);
    }

    if !bin_items.is_empty() {
        packed.push(bin_items);
    }

    packed
}

/// Split data files for batch reading using bin packing.
///
/// Files are sorted by `min_sequence_number`, then packed into groups where each group's
/// total weight (using `max(file_size, open_file_cost)` as per-file weight) does not
/// exceed `target_split_size`.
///
/// Reference: [AppendOnlySplitGenerator.splitForBatch](https://github.com/apache/paimon/blob/master/paimon-core/src/main/java/org/apache/paimon/table/source/AppendOnlySplitGenerator.java)
pub fn split_for_batch(
    mut files: Vec<DataFileMeta>,
    target_split_size: i64,
    open_file_cost: i64,
) -> Vec<Vec<DataFileMeta>> {
    files.sort_by_key(|f| f.min_sequence_number);
    let weight_func = move |f: &DataFileMeta| cmp::max(f.file_size, open_file_cost);
    pack_for_ordered(files, weight_func, target_split_size)
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::spec::stats::BinaryTableStats;
    use chrono::{DateTime, Utc};

    fn make_file(file_name: &str, file_size: i64, min_seq: i64, max_seq: i64) -> DataFileMeta {
        DataFileMeta {
            file_name: file_name.to_string(),
            file_size,
            row_count: 100,
            min_key: Vec::new(),
            max_key: Vec::new(),
            key_stats: BinaryTableStats::new(Vec::new(), Vec::new(), Vec::new()),
            value_stats: BinaryTableStats::new(Vec::new(), Vec::new(), Vec::new()),
            min_sequence_number: min_seq,
            max_sequence_number: max_seq,
            schema_id: 0,
            level: 0,
            extra_files: Vec::new(),
            creation_time: DateTime::<Utc>::from_timestamp(0, 0),
            delete_row_count: None,
            embedded_index: None,
            first_row_id: None,
            write_cols: None,
            external_path: None,
            file_source: None,
            value_stats_cols: None,
        }
    }

    #[test]
    fn test_pack_for_ordered_empty() {
        let result: Vec<Vec<i32>> = pack_for_ordered(vec![], |_| 1, 10);
        assert!(result.is_empty());
    }

    #[test]
    fn test_pack_for_ordered_single_oversized() {
        let result = pack_for_ordered(vec![100], |x| *x, 10);
        assert_eq!(result, vec![vec![100]]);
    }

    #[test]
    fn test_pack_for_ordered_all_fit_in_one_bin() {
        let result = pack_for_ordered(vec![1, 2, 3], |x| *x, 100);
        assert_eq!(result, vec![vec![1, 2, 3]]);
    }

    /// Matches Java SplitGeneratorTest with targetSplitSize=40, openFileCost=2.
    #[test]
    fn test_split_for_batch_low_open_cost() {
        let files = vec![
            make_file("1", 11, 0, 20),
            make_file("2", 13, 21, 30),
            make_file("3", 46, 31, 40),
            make_file("4", 23, 41, 50),
            make_file("5", 4, 51, 60),
            make_file("6", 101, 61, 100),
        ];

        let groups = split_for_batch(files, 40, 2);
        let names: Vec<Vec<&str>> = groups
            .iter()
            .map(|g| g.iter().map(|f| f.file_name.as_str()).collect())
            .collect();
        assert_eq!(
            names,
            vec![vec!["1", "2"], vec!["3"], vec!["4", "5"], vec!["6"]]
        );
    }

    /// Matches Java SplitGeneratorTest with targetSplitSize=40, openFileCost=20.
    #[test]
    fn test_split_for_batch_high_open_cost() {
        let files = vec![
            make_file("1", 11, 0, 20),
            make_file("2", 13, 21, 30),
            make_file("3", 46, 31, 40),
            make_file("4", 23, 41, 50),
            make_file("5", 4, 51, 60),
            make_file("6", 101, 61, 100),
        ];

        let groups = split_for_batch(files, 40, 20);
        let names: Vec<Vec<&str>> = groups
            .iter()
            .map(|g| g.iter().map(|f| f.file_name.as_str()).collect())
            .collect();
        assert_eq!(
            names,
            vec![vec!["1", "2"], vec!["3"], vec!["4"], vec!["5"], vec!["6"]]
        );
    }

    /// Verify files are sorted by min_sequence_number before packing.
    #[test]
    fn test_split_for_batch_sorts_by_sequence() {
        let files = vec![
            make_file("c", 10, 30, 40),
            make_file("a", 10, 10, 20),
            make_file("b", 10, 20, 30),
        ];

        let groups = split_for_batch(files, 1000, 0);
        assert_eq!(groups.len(), 1);
        let names: Vec<&str> = groups[0].iter().map(|f| f.file_name.as_str()).collect();
        assert_eq!(names, vec!["a", "b", "c"]);
    }

    #[test]
    fn test_split_for_batch_empty() {
        let groups = split_for_batch(vec![], 128, 4);
        assert!(groups.is_empty());
    }
}