Json Indexer

json对象的多值索引器。

此crate允许根据点路径创建json对象的排序映射，类似于数据库如mongodb根据路径生成和索引，此crate旨在用于创建非关系型数据库。此库被创建用于作为escanordb的索引结构。

通往0.3的道路：待办事项

• 数组查询运算符
  • 包含：all
  • 包含任意：any
  • 在：in

通往0.2的道路：待办事项

• 基本查询支持
  • 运算符 eq lt gt
  • 限制查询输出
  • like (MS SQL LIKE *ja*)
• 复合查询
• 排序

版本0.1.5

功能

• 基本查询请参阅以下文档

示例

单个索引

本示例演示了如何使用json索引器索引一个json值

    let gpa_order = JsonPathOrder {
        path: "gpa".to_string(),
        ordering: IndexOrd::DESC,
    };

    let name_order = JsonPathOrder {
        path: "name".to_string(),
        ordering: IndexOrd::ASC,
    };

    let state_order = JsonPathOrder {
        path: "state".to_string(),
        ordering: IndexOrd::ASC,
    };

    let indexer = Indexer::Json(IndexJson {
        path_orders: vec![name_order, gpa_order, state_order]
    });

    let mut students_index = Index::new(indexer);
    students_index.insert("student:0", Student {
        name: "Mambisi".to_owned(),
        age: 21,
        state: "CA".to_owned(),
        gpa: 3.1,
    });
    students_index.insert("student:1", Student {
        name: "Joseph".to_owned(),
        age: 12,
        state: "CA".to_owned(),
        gpa: 3.1,
    });
    students_index.insert("student:2", Student {
        name: "Elka".to_owned(),
        age: 12,
        state: "FL".to_owned(),
        gpa: 4.0,
    });

    students_index.insert("student:18", Student {
        name: "Alex".to_owned(),
        age: 15,
        state: "NY".to_owned(),
        gpa: 3.7,
    });

    students_index.insert("student:18", Student {
        name: "Jackson".to_owned(),
        age: 17,
        state: "NY".to_owned(),
        gpa: 3.8,
    });



    let query = students_index.find_where("state", Op::EQ, "CA");
    println!("Find all students in CA: {:?}", query.get());

    let query = students_index.find_where("gpa", Op::GT, 3.5);
    println!("Find all students whose gpa greater than 3.5: {:?}", query.get());



    let string_indexer = Indexer::String(IndexString {
        ordering: IndexOrd::ASC
    });

    let mut names_index = Index::new(string_indexer);
    names_index.batch(|b| {
        b.insert("user.1", "Kwadwo");
        b.insert("user.9", "Kwadwo");
        b.insert("user.8", "Kwabena");
        b.insert("user.2", "Kwame");
        b.insert("user.3", "Joseph");
        b.insert("user.4", "Jake");
        b.insert("user.5", "Mambisi");
        b.insert("user.6", "Ama");
        b.commit()
    });

    println!("Index Tree: {}", serde_json::to_string_pretty(&names_index).unwrap());

    names_index.remove("user.1");
    let res = names_index.find_where("*", Op::LIKE, Value::String("k*".to_string()));
    println!("users whose name starts with K");
    println!("{:?}", res.get());
/* Output
Find all students in CA: [
    ("student:1", Object({"age": Number(12), "gpa": Number(3.1), "name": String("Joseph"), "state": String("CA")})),
    ("student:0", Object({"age": Number(21), "gpa": Number(3.1), "name": String("Mambisi"), "state": String("CA")}))
]
Find all students whose gpa greater than 3.5: [
    ("student:18", Object({"age": Number(17), "gpa": Number(3.8), "name": String("Jackson"), "state": String("NY")})),
    ("student:2", Object({"age": Number(12), "gpa": Number(4.0), "name": String("Elka"), "state": String("FL")}))
]
users whose name starts with K
[
    ("user.2", String("Kwame")),
    ("user.8", String("Kwadwo")),
    ("user.1", String("Kwadwo"))
]
*/

多索引与点路径

本示例演示了如何使用json索引器使用多个点路径索引整个json对象

下载样本数据文件 MOVIES_JSON_FILE

    let movie_json_file = env::var("MOVIES_JSON_FILE").unwrap();
    let file = File::open(movie_json_file).unwrap();
    let reader = BufReader::new(file);
    let json: Value = serde_json::from_reader(reader).unwrap();
    let list = json.as_array().unwrap();

    let title_order = JsonPathOrder {
        path: "title".to_string(),
        ordering: IndexOrd::ASC,
    };

    let release_date_order = JsonPathOrder {
        path: "release_date".to_string(),
        ordering: IndexOrd::DESC,
    };

    let indexer = Indexer::Json(IndexJson {
        path_orders: vec![release_date_order, title_order.to_owned()]
    });

    let mut index = Index::new(indexer);

    index.batch(|b| {
        let timer = Instant::now();
        list.iter().for_each(|v| {
            let key = v.dot_get_or("id", Value::String("".to_string())).unwrap();
            b.insert(key.as_str().unwrap(), v.clone())
        });
        b.commit();
        let total_time = timer.elapsed().as_secs_f64();
        println!("Indexed list of size: {:?} in {} secs", list.len(), total_time);
    });

    drop(json);

    let timer = Instant::now();

    let order_indexer = Indexer::Json(IndexJson {
        path_orders: vec![title_order.clone()]
    });

    let mut query = index.find_where("title", Op::LIKE, "Jumanji*");
    let found = query.count();

    let completion_time = timer.elapsed().as_millis();
    println!("query completed in {} ms, found {} items", completion_time, found);


    println!("Showing Results: release date");
    query.order_by(order_indexer).limit(10).get().iter().for_each(|(k, v)| {
        println!("{}:{}", k, serde_json::to_string_pretty(v).unwrap());
    })
/* outputs
Indexed list of size: 19653 in 1.043351253 secs
query completed in 10 ms, found 3 items
Showing Results: release date
512200:{
  "id": "512200",
  "overview": "Plot kept under wraps.",
  "poster": "https://image.tmdb.org/t/p/w1280null",
  "release_date": 1576022400,
  "title": "Jumanji 3"
}
353486:{
  "id": "353486",
  "overview": "The tables are turned as four teenagers are sucked into Jumanji's world - pitted against rhinos, black mambas and an endless variety of jungle traps and puzzles. To survive, they'll play as characters from the game.",
  "poster": "https://image.tmdb.org/t/p/w1280/bXrZ5iHBEjH7WMidbUDQ0U2xbmr.jpg",
  "release_date": 1512777600,
  "title": "Jumanji: Welcome to the Jungle"
}
8844:{
  "id": "8844",
  "overview": "When siblings Judy and Peter discover an enchanted board game that opens the door to a magical world, they unwittingly invite Alan -- an adult who's been trapped inside the game for 26 years -- into their living room. Alan's only hope for freedom is to finish the game, which proves risky as all three find themselves running from giant rhinoceroses, evil monkeys and other terrifying creatures.",
  "poster": "https://image.tmdb.org/t/p/w1280/vgpXmVaVyUL7GGiDeiK1mKEKzcX.jpg",
  "release_date": 818985600,
  "title": "Jumanji"
}
*/