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

// Copyright 2024 Lance Developers.
//
// Licensed 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.

use std::sync::Arc;

use async_trait::async_trait;
use lance_core::Result;

use crate::{optimize::OptimizeOptions, IndexParams, IndexType};
use lance_table::format::Index;

// Extends Lance Dataset with secondary index.
///
#[async_trait]
pub trait DatasetIndexExt {
    /// Create indices on columns.
    ///
    /// Upon finish, a new dataset version is generated.
    ///
    /// Parameters:
    ///
    ///  - `columns`: the columns to build the indices on.
    ///  - `index_type`: specify [`IndexType`].
    ///  - `name`: optional index name. Must be unique in the dataset.
    ///            if not provided, it will auto-generate one.
    ///  - `params`: index parameters.
    ///  - `replace`: replace the existing index if it exists.
    async fn create_index(
        &mut self,
        columns: &[&str],
        index_type: IndexType,
        name: Option<String>,
        params: &dyn IndexParams,
        replace: bool,
    ) -> Result<()>;

    /// Read all indices of this Dataset version.
    ///
    /// The indices are lazy loaded and cached in memory within the [`Dataset`] instance.
    /// The cache is invalidated when the dataset version (Manifest) is changed.
    async fn load_indices(&self) -> Result<Arc<Vec<Index>>>;

    /// Loads all the indies of a given UUID.
    ///
    /// Note that it is possible to have multiple indices with the same UUID,
    /// as they are the deltas of the same index.
    async fn load_index(&self, uuid: &str) -> Result<Option<Index>> {
        self.load_indices().await.map(|indices| {
            indices
                .iter()
                .find(|idx| idx.uuid.to_string() == uuid)
                .cloned()
        })
    }

    /// Loads a specific index with the given index name
    ///
    /// Returns
    /// -------
    /// - `Ok(indices)`: if the index exists, returns the index.
    /// - `Ok(vec![])`: if the index does not exist.
    /// - `Err(e)`: if there is an error loading indices.
    ///
    async fn load_indices_by_name(&self, name: &str) -> Result<Vec<Index>> {
        self.load_indices().await.map(|indices| {
            indices
                .iter()
                .filter(|idx| idx.name == name)
                .cloned()
                .collect()
        })
    }

    /// Loads a specific index with the given index name.
    async fn load_scalar_index_for_column(&self, col: &str) -> Result<Option<Index>>;

    /// Optimize indices.
    async fn optimize_indices(&mut self, options: &OptimizeOptions) -> Result<()>;

    /// Find index with a given index_name and return its serialized statistics.
    ///
    /// If the index does not exist, return Error.
    async fn index_statistics(&self, index_name: &str) -> Result<String>;
}