MongoDB Common Commands

MongoDB Common Commands

From Kiinlam

Installation

MongoDB official website Download installation (Windows installation method)

Basic knowledge

Collections-Tables in the corresponding relational database

Documents--correspond to rows in a relational database

Start the database service

After locating in the Bin folder in the installation directory

> mongod --dbpath ../data/db

If you don't have data/db a folder, you need to create it to dbpath specify where the data is stored

Open a Client Access database

Execute under the same Bin folder

> mongo

Connect to database by default test

Show Help

> help

Show all database names

> show dbs

Switch database

> use test

Displays the database name of the current connection

> db

Display all collections of the current database

> show collections

Show the methods supported by the database

> db.help()

Show supported Methods for collections

> db.users.help()

Create a Collection

> db.createCollection("users")

Inserting action Insert

> db.users.insert({"name":"kiinlam","age":28})

Query operations find Find all documents

> db.users.find()

Find the specified document

> db.users.find({"name":"kiinlam"})

Query A

> db.users.findOne({"name":"kiinlam"})

Greater than $GT

> db.users.find({"age":{$gt:22}})

Greater than or equal to $gte

> db.users.find({"age":{$gte:22}})

Less than $LT

> db.users.find({"age":{$lt:22}})

Less than or equal to $gte

> db.users.find({"age":{$lte:22}})

Not equal to $ne

> db.users.find("age":{$ne:22})

or $or

> db.users.find({$or:[{"name":"kiinlam"},{"name":"cheungkiinlam"}]})

$in in the collection

> db.users.find("name":{$in:["kiinlam","cheungkiinlam"]})

Not $nin in collection

> db.users.find("name":{$nin:["kiinlam","cheungkiinlam"]})

Regular queries

> db.users.find({"name":/^k/,"name":/m$/})

Filter Query $where

// 使用js function作为筛选条件> db.users.find({$where: function(){return this.name==‘kiinlam‘}})

Limiting the number of queries limit

> db.users.find({"age":22}).limit(10)

Update action updates Specifies that the document is all updated, equal to overwrite

> db.users.update({"name":"kiinlam"}, {"name":"cheungkiinlam","age":27})

Partial update One: Incremental update $inc

// age增加2，其他不变> db.users.update({"name":"kiinlam"}, {$inc:{"age":2}})

Partial update two: Field modification $set

// age改为20> db.users.update({"name":"kiinlam"}, {$set:{"age":20}})

New update: If it doesn't exist, add a new one

// 第三个参数为true> db.users.update({"name":"kiinlam"}, {$set:{"age":18}}, true)

Batch Update

// 如果匹配多条，默认只改第一条，将第四个参数设为true可全部更新> db.users.update({"name":"kiinlam"}, {$set:{"age":18}}, true, true)

Save Operation Save

// 插入新文档，如果不提供"_id"字段> db.users.save({"name":"kiinlam", "age":28})// 更新已存在的文档> db.users.save({"_id":"xxx","name":"kiinlam", "age":28})

Remove Operation Remove

Delete Operation not recoverable

Delete all but do not delete the index

> db.users.remove({})

Delete the specified document

> db.users.remove({"name":"kiinlam"})

Deletes a specified document, if there are multiple results

> db.users.remove({"name":"kiinlam"}, true)

Completely delete the collection, including the index, you should use thedrop

When a large number of deletions are made, copy the documents that need to be persisted to the new collection, and then drop delete the collection.

Deleting a database

> db.dropDatabase()

Delete Collection

> db.users.drop()

Count Operation Count

> db.users.count()> db.users.count({"age":29})

Unique value query distinct specifies that the field has multiple simultaneous, one-to-many, and returns an array of the values of the specified field

> db.users.distinct("age")

Group Operations Group

agegrouped results are stored in user , and the value is an array of corresponding age name values, as per the grouping operation

key: Group on

initial: Initialize function, each different age group shares the same function

$reduce: The first parameter is the current document, the second parameter is the cumulative object of the previous function operation, and the first one is the initial corresponding object

> db.users.group({                    "key": {"age": true},                    "initial": {"user": []},                    "$reduce": function(cur,prev){                        prev.user.push(cur.name);                    }                })

Suppose you have the following data:

{ "_id" : ObjectId("55910457607379845607d9e2"), "name" : "kiinlam", "age" : 29 }{ "_id" : ObjectId("55910468607379845607d9e3"), "name" : "shadow", "age" : 26 }{ "_id" : ObjectId("55910992607379845607d9e5"), "name" : "foo", "age" : 29 }{ "_id" : ObjectId("55911fca607379845607d9e6"), "name" : "dd", "age" : 22 }{ "_id" : ObjectId("55911fd3607379845607d9e7"), "name" : "mm", "age" : 22 }{ "_id" : ObjectId("55911fdf607379845607d9e8"), "name" : "gg", "age" : 22 }{ "_id" : ObjectId("55911feb607379845607d9e9"), "name" : "jj", "age" : 22 }{ "_id" : ObjectId("55920545ff40738c1fd0a839"), "name" : "zz", "age" : 1 }

The result of the grouping is:

[        {                "age" : 29,                "user" : [                        "kiinlam",                        "foo"                ]        },        {                "age" : 26,                "user" : [                        "shadow"                ]        },        {                "age" : 22,                "user" : [                        "dd",                        "mm",                        "gg",                        "jj"                ]        },        {                "age" : 1,                "user" : [                        "zz"                ]        }]

More grouping features

Optional parameters: condition and finalize .

`condition` —— 过滤条件`finalize` —— 函数，分组完成后执行

Filter out age documents greater than 22, add attributes to indicate the number of files in the group

> db.users.group({                    "key": {"age": true},                    "initial": {"user": []},                    "$reduce": function(cur,prev){                        prev.user.push(cur.name);                    },                    "condition": {"age":{$lte:22}},                    "finalize": function(out){                        out.count = out.user.length;                    }                })

The result of the grouping is:

[        {                "age" : 22,                "user" : [                        "dd",                        "mm",                        "gg",                        "jj"                ],                "count" : 4        },        {                "age" : 1,                "user" : [                        "zz"                ],                "count" : 1        }]

Mapreduce

map: Mapping functions, internal calls emit(key,value) , collections key are grouped by mapping.

reduce: Simplification of functions, grouping map of data after grouping simplification, in the reduce(key,value) key emit Middle key , and value then is emit the collection of grouped results.

mapReduce: The last function to execute, the parameter is map , reduce and some optional arguments.

> db.users.mapReducefunction ( map , reduce , optionsOrOutString ){    var c = { mapreduce : this._shortName , map : map , reduce : reduce };    assert( optionsOrOutString , "need to supply an optionsOrOutString" )    if ( typeof( optionsOrOutString ) == "string" )        c["out"] = optionsOrOutString;    else        Object.extend( c , optionsOrOutString );    var raw = this._db.runCommand( c );    if ( ! raw.ok ){        __mrerror__ = raw;        throw Error( "map reduce failed:" + tojson(raw) );    }    return new MapReduceResult( this._db , raw );}

Create a map function

function (){    emit(this.name,{count:1});}

Create a reduce function

function (key,value){    var result = {count:0};    for(var i = 0; i < value.length; i++){        result.count += value[i].count;    }    return result;}

Perform mapReduce actions

> db.users.mapReduce(map,reduce,{"out":"collection"})

Suppose you have the following data

{ "_id" : ObjectId("55910457607379845607d9e2"), "name" : "kiinlam", "age" : 29 }{ "_id" : ObjectId("55910468607379845607d9e3"), "name" : "shadow", "age" : 26 }{ "_id" : ObjectId("55910992607379845607d9e5"), "name" : "foo", "age" : 29 }{ "_id" : ObjectId("55920545ff40738c1fd0a839"), "name" : "zz", "age" : 1 }{ "_id" : ObjectId("55911fca607379845607d9e6"), "name" : "foo", "age" : 22 }{ "_id" : ObjectId("55911fd3607379845607d9e7"), "name" : "foo", "age" : 22 }{ "_id" : ObjectId("55911fdf607379845607d9e8"), "name" : "foo", "age" : 22 }{ "_id" : ObjectId("55911feb607379845607d9e9"), "name" : "foo", "age" : 22 }

Output results

{        "result" : "collection",    // 存放最终结果的集合名        "timeMillis" : 28,        "counts" : {                "input" : 8,    // 传入文档的次数                "emit" : 8,    // emit函数被调用次数                "reduce" : 1,    // reduce函数被调用次数                "output" : 4    // 最后返回文档的个数        },        "ok" : 1}

To view collection the results in a collection

> db.collection.find()

Output results

{ "_id" : "foo", "value" : { "count" : 5 } }{ "_id" : "kiinlam", "value" : { "count" : 1 } }{ "_id" : "shadow", "value" : { "count" : 1 } }{ "_id" : "zz", "value" : { "count" : 1 } }

Cursor

A cursor represents only a reference, not a real execution, and, when needed, iterates through a for loop or next() method, and when the enumeration finishes, the cursor is destroyed and no longer returns data.

Declare a cursor

> var list = db.collection.find()

By forEach traversing a cursor

> list.forEach(function(i){      print(i._id);  })

Output results

fookiinlamshadowzz

or by next iterating through the collection

> var list = db.collection.find()> list.next(){ "_id" : "foo", "value" : { "count" : 5 } }> list.next(){ "_id" : "kiinlam", "value" : { "count" : 1 } }> list.next(){ "_id" : "shadow", "value" : { "count" : 1 } }> list.next(){ "_id" : "zz", "value" : { "count" : 1 } }> list.next()2015-07-01T11:27:38.186+0800 E QUERY    Error: error hasNext: false    at Error (<anonymous>)    at DBQuery.next (src/mongo/shell/query.js:255:15)    at (shell):1:6 at src/mongo/shell/query.js:255> list>

Index Ensureindex Index

// 1为升序，-1为降序> db.users.ensureIndex({"name":1})

Unique index

> db.users.ensureIndex({"name":1},{"unique":true})

Combined index

> db.users.ensureIndex({"name":1, "age":-1})

View Index

> db.users.getIndexes()

Query by specified index

> db.users.find({"name":"kiinlam"}).hint({"name":1,"age":1})

Delete Index

// 删除所有自定义索引> db.users.dropIndexes()// 删除指定索引> db.users.dropIndex("name_1")

Performance analysis Function explain

> db.users.find().explain("executionStats")

Master-Slave database deployment Create primary database Master

> mongod --dbpath=XXX --master

Create a slave from a database

// 指定从数据库端口--port// 指定主数据库源--source> mongod --dbpath=XXX --port=8888 --slave --source=127.0.0.1:27017

Specify the primary database source later

> mongod --dbpath=XXX --port=8888 --slave// 后期添加源// 切换到local数据库> use local// 在sources中加入源地址> db.sources.insert({"host":"127.0.0.1:27017"})

Replica set Replset

The schema does not have a specific primary database, one database is down, and the other database is on top

Create the first database server

// 需要指定集群名及下一个数据库地址> mongod --dbpath=XXX --port 2222 --replSet mySet/127.0.0.1:3333

Create a second database server

> mongod --dbpath=XXX --port 3333 --replSet mySet/127.0.0.1:2222

Initializing a replica set

// 进入任一数据库的admin集合> mongo 127.0.0.1:2222/admin// 执行初始化操作> db.runCommand({                    "replSetInitiate":{                        "_id":"mySet",                        "members":[                            {                                "_id":1,                                "host":"127.0.0.1:2222"                            },                            {                                "_id":2,                                "host":"127.0.0.1:3333"                            }                        ]                    }                })

Arbiter Server

// 启动仲裁服务器> mongod --dbpath=XXX --port 4444 --replSet mySet/127.0.0.1:2222// 回到admin集合中添加仲裁服务器> mongo 127.0.0.1:2222/admin> rs.addArb("127.0.0.1:4444")// 查看服务器集群状态> rs.status()

Shard Technology

Splits the collection to divide the split data over several shards.

Main players:

• Client
• Routing Server MONGOs
• Configure the server
• Shard DB Instance

Turn on Configuration server Config

> mongod --dbpath=XXX --port 2222

Turn on the routing server MONGOs

// 指定配置服务器> mongos --port 3333 --configdb=127.0.0.1:2222

Open the Shard database server Mongod

> mongod --dbpath=XXX --port 4444> mongod --dbpath=XXX --port 5555

Service configuration

// 进入mongos数据库admin集合> mongo 127.0.0.1:3333/admin// 添加分片服务器addshard> db.runCommand({                    "addshard":"127.0.0.1:4444",                    "allowLocal":true                })> db.runCommand({                    "addshard":"127.0.0.1:5555",                    "allowLocal":true                })// 开启数据库test的分片功能enablesharding> db.runCommand({"enablesharding":"test"})// 指定集合中分片的片键users.name> db.runCommand({"shardcollection":"test.users","key":{"name":1}})// 在mongos中查看数据分片情况> use test> db.printShardingStatus()

Operation and Maintenance

Operations typically involve the following 4 areas

• Installation deployment
• Status monitoring
• Security Certifications
• Backup and Recovery

Install the deployment as a Windows service

// 指定日志路径，添加install参数> mongod --dbpath=XXX --logpath=XXX --port=2222 --install// 启动服务> net start MongoDB

State Monitoring Static statistics

Db.stats ()

// 查看单个数据库状态> db.stats()

statsRelatively simple, you can refer to the db.stats () article

Db.serverstatus ()

// 查看整个mongodb的状态// 进入admin集合> mongo 127.0.0.1:2222/admin// 查看状态> db.serverStatus()

serverStatusA lot of parameters, you can refer to the Db.serverstatus () article

Real-time statistics

> mongostat --port 2222

Security Certifications

Todo

A little complicated, lazy, reference safety certification

Backup and Recovery

// 备份test数据库到D:\mongodb\backup> mongodump --port 2222 -d test -o D:\mongodb\backup// 恢复数据，drop表示恢复前删除原有数据> mongorestore --port 2222 -d test --drop D:\mongodb\backup

Resources

• Mongodb
• MongoDB Documentation
• Install-mongodb-on-windows
• 8-Day learning through MongoDB series

MongoDB Common Commands