重庆思庄Oracle、、PostgreSQL、Redhat认证学习论坛

标题: 在MongoDB中创建索引，删除索引，查找索引 [打印本页]

作者: 郑全 时间: 2023-10-6 12:43
标题: 在MongoDB中创建索引，删除索引，查找索引
可以使用 ensueIndex ,或者 createIndex ,不过，mongoDB 3.0开始，ensueIndex  已经已经被废弃，所以，建议使用createIndex创建INDEX。

--1.数据情况

db.employees.find();
{ "_id" : ObjectId("64a8e771c531db7498ca2081"), "empid" : 100, "name" : "mahan", "age" : 30 }
{ "_id" : ObjectId("64a8e795c531db7498ca2082"), "empid" : 101, "name" : "liuzy", "age" : 25 }
{ "_id" : ObjectId("64a8e7e3c531db7498ca2083"), "empid" : 102, "name" : "wangjia", "age" : 30, "hire_date" : "2012-10-10" }
{ "_id" : ObjectId("64a8e841c531db7498ca2084"), "empid" : 103, "name" : "zengyin", "age" : 32, "hire_date" : "2018-09-10", "job" : "sales" }

比如，我们想在 employees.empid上创建索引：
--2.创建索引
db.employees.createIndex({empid:1});

db.employees.createIndex({empid:1});
{
      "createdCollectionAutomatically" : false,
      "numIndexesBefore" : 1,
      "numIndexesAfter" : 2,
      "ok" : 1
}

--3.查找EMPLOYEES集合的索引索引

> db.employees.getIndexes();
[
      {
            "v" : 2,
            "key" : {
                     "_id" : 1
            },
            "name" : "_id_",
            "ns" : "ordb.employees"
      },
      {
            "v" : 2,
            "key" : {
                     "empid" : 1
            },
            "name" : "empid_1",
            "ns" : "ordb.employees"
      }
]

--4.删除索引

> db.employees.dropIndex({empid:1});
{ "nIndexesWas" : 2, "ok" : 1 }

--5.再次确认索引被删除

> db.employees.getIndexes();
[
      {
            "v" : 2,
            "key" : {
                     "_id" : 1
            },
            "name" : "_id_",
            "ns" : "ordb.employees"
      }
]

欢迎光临重庆思庄Oracle、、PostgreSQL、Redhat认证学习论坛 (http://bbs.cqsztech.com/)