IV.Indexes(索引)

最新推荐文章于 2025-07-02 12:56:36 发布

Owen William

最新推荐文章于 2025-07-02 12:56:36 发布

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分类专栏： MongoDB

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本文详细介绍了如何在MongoDB中创建、管理和优化索引，包括单字段索引、复合索引、文本索引、哈希索引以及2dsphere索引的使用。还涵盖了TTL索引、唯一索引、部分索引和稀疏索引等特性，以及索引在查询、排序和性能优化中的应用策略。

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Recipe 4-1. Working with Indexes(使用索引)
   准备数据
       db.employee.insert({empId:1,empName:"John",state:"KA",country:"India"})
       db.employee.insert({empId:2,empName:"Smith",state:"CA",country:"US"})
       db.employee.insert({empId:3,empName:"James",state:"FL",country:"US"})
       db.employee.insert({empId:4,empName:"Josh",state:"TN",country:"India"})
       db.employee.insert({empId:5,empName:"Joshi",state:"HYD",country:"India"})
   1.创建索引
       db.employee.createIndex({empId:1})
   2.创建多个域的索引
       db.employee.createIndex({empId:1,empName:1})
   3.查看索引
       db.employee.getIndexes()
   4.删除指定索引
       db.employee.dropIndex({empId:1,empName:1})
   5.删除所有索引
       db.employee.dropIndexes()
   6.注意_id是默认索引，是不能删除
Recipe 4-2. Index Types(索引类型)
   准备数据
       db.employeeproject.insert({empId:1001,empName:"John",projects:["Hadoop","MongoDB"]})
       db.employeeproject.insert({empId:1002,empName:"James",projects:["MongoDB","Spark"]})
   1.多个key的索引--即指定数据中的某个作为索引
       db.employeeproject.createIndex({projects:1})
   2.文本索引
       有这样的数据
           db.post.insert({
               "post_text": "Happy Learning",
               "tags": [
               "mongodb",
               "10gen"
               ]
           })
       创建索引：db.post.createIndex({post_text:"text"})
       查询：db.post.find({$text:{$search:"Happy"}})
   3.Hashed索引
       有这样的数据
           db.user.insert({userId:1,userName:"John"})
           db.user.insert({userId:2,userName:"James"})
           db.user.insert({userId:3,userName:"Jack"})
       创建Hashed索引：db.user.createIndex( { userId: "hashed" } )
   4.2dsphere索引
       有这样的数据
           db.schools.insert( {name: "St.John's School",location: { type: "Point", coordinates: [ -73.97, 40.77 ] },} );
           db.schools.insert( {name: "St.Joseph's School",location: { type: "Point", coordinates: [ -73.9928, 40.7193 ] },} );
           db.schools.insert( {name: "St.Thomas School",location: { type: "Point", coordinates: [ -73.9375, 40.8303 ] },} );
       创建索引：db.schools.createIndex( { location : "2dsphere" } )
       查询(位置)：
           db.schools.find({location:{$near:{$geometry: { type:"Point", coordinates: [ -73.9667, 40.78 ] },$minDistance:500,$maxDistance: 1500}}})

Recipe 4-3. Index Properties(索引属性)

   1.TTL索引
   准备数据
       db.credit.insert({credit:16})
       db.credit.insert({credit:18})
       db.credit.insert({credit:12})
       创建索引：db.credit.createIndex( { credit: 1 }, { expireAfterSeconds: 35 } );
   2.Unique索引
       准备数据
           db.student.insert({_id:1,studid:101,studname:"John"})
           db.student.insert({_id:2,studid:102,studname:"Jack"})
           db.student.insert({_id:3,studid:103,studname:"James"})
       创建索引：db.student.createIndex({"studid":1}, {unique:true})
       插入数据会报错：db.student.insert([{_id:1,studid:101,studname:"John"}])
   3.Partial索引
       可以使用的操作符：$exists,$gt,$gte,$lt,$lte,$type,$and
       准备数据
           db.person.insert({personName:"John",age:16})
           db.person.insert({personName:"James",age:15})
           db.person.insert({personName:"John",hobbies:["sports","music"]})
       创建索引
           db.person.createIndex( { age: 1},{partialFilterExpression: {age: { $gt: 15 }}})
       查询：db.person.find( { age: { $gt: 15 } } )
   4.Sparse索引
       准备数据
           db.person.insert({personName:"John",age:16})
           db.person.insert({personName:"James",age:15})
           db.person.insert({personName:"John",hobbies:["sports","music"]})
       创建索引
           db.person.createIndex( { age: 1 }, { sparse: true } );
       查询：db.person.find().hint( { age: 1 } ).count();
               db.person.find().count();
Recipe 4-4. Indexing Strategies(索引策略)
   1.创建索引用于查询
       db.employee.createIndex({empId:1})
       db.employee.createIndex({empId:1,empName:1})
   2.使用索引来排序结果
       db.employee.createIndex({empId:1})
       db.employee.find().sort({empId:1})
   3.排序多个域
       db.employee.createIndex({empId:1,empName:1})
       db.employee.find().sort({empId:1,empName:1})
   4.查询索引可以使用的大小
       db.employee.totalIndexSize()