1.MongoDB 命令帮助系统
在安装MongoDB后，启动服务器进程（mongod），可以通过在客户端命令mongo实现对MongoDB的管理和监控。
1.1MongoDB的命令帮助系统
> help
db.help() help on db methods
db.mycoll.help() help on collection methods
sh.help() sharding helpers
rs.help() replica set helpers
help admin administrative help
help connect connecting to a db help
help keys key shortcuts
help misc misc things to know
help mr mapreduce
show dbs show database names
show collections show collections in current database
show users show users in current database
show profile show most recent system.profile entries with time >= 1ms
show logs show the accessible logger names
show log [name] prints out the last segment of log in memory, 'global' is default
use <db_name> set current database
db.foo.find() list objects in collection foo
db.foo.find( { a : 1 } ) list objects in foo where a == 1
it result of the last line evaluated; use to further iterate
DBQuery.shellBatchSize = x set default number of items to display on shell
exit quit the mongo shell
>
这是MongoDB最顶层的命令列表，主要告诉我们管理数据库相关的一些抽象的范畴：数据库操作帮助、集合操作帮助、管理帮助。如果你想了解数据库操作更详细的帮助命令，可以直接使用db.help()，如下所示：
> db.help()
DB methods:
db.adminCommand(nameOrDocument) - switches to 'admin' db, and runs command [just calls db.runCommand(...)]
db.aggregate([pipeline], {options}) - performs a collectionless aggregation on this database; returns a cursor
db.auth(username, password)
db.cloneDatabase(fromhost)
db.commandHelp(name) returns the help for the command
db.copyDatabase(fromdb, todb, fromhost)
db.createCollection(name, {size: ..., capped: ..., max: ...})
db.createView(name, viewOn, [{$operator: {...}}, ...], {viewOptions})
db.createUser(userDocument)
db.currentOp() displays currently executing operations in the db
db.dropDatabase()
db.eval() - deprecated
db.fsyncLock() flush data to disk and lock server for backups
db.fsyncUnlock() unlocks server following a db.fsyncLock()
db.getCollection(cname) same as db['cname'] or db.cname
db.getCollectionInfos([filter]) - returns a list that contains the names and options of the db's collections
db.getCollectionNames()
db.getLastError() - just returns the err msg string
db.getLastErrorObj() - return full status object
db.getLogComponents()
db.getMongo() get the server connection object
db.getMongo().setSlaveOk() allow queries on a replication slave server
db.getName()
db.getPrevError()
db.getProfilingLevel() - deprecated
db.getProfilingStatus() - returns if profiling is on and slow threshold
db.getReplicationInfo()
db.getSiblingDB(name) get the db at the same server as this one
db.getWriteConcern() - returns the write concern used for any operations on this db, inherited from server object if set
db.hostInfo() get details about the server's host
db.isMaster() check replica primary status
db.killOp(opid) kills the current operation in the db
db.listCommands() lists all the db commands
db.loadServerScripts() loads all the scripts in db.system.js
db.logout()
db.printCollectionStats()
db.printReplicationInfo()
db.printShardingStatus()
db.printSlaveReplicationInfo()
db.dropUser(username)
db.repairDatabase()
db.resetError()
db.runCommand(cmdObj) run a database command. if cmdObj is a string, turns it into {cmdObj: 1}
db.serverStatus()
db.setLogLevel(level,<component>)
db.setProfilingLevel(level,slowms) 0=off 1=slow 2=all
db.setWriteConcern(<write concern doc>) - sets the write concern for writes to the db
db.unsetWriteConcern(<write concern doc>) - unsets the write concern for writes to the db
db.setVerboseShell(flag) display extra information in shell output
db.shutdownServer()
db.stats()
db.version() current version of the server
>
对数据库进行管理和操作的基本命令，可以从上面获取到。如果想要得到更多，而且每个命令的详细用法，可以使用上面列出的db.listCommands()查询。另一个比较基础的是对指定数据库的集合进行操作、管理和监控，可以通过查询db.mycoll.help()获取到：
> db.mycoll.help()
DBCollection help
db.mycoll.find().help() - show DBCursor help
db.mycoll.bulkWrite( operations, <optional params> ) - bulk execute write operations, optional parameters are: w, wtimeout, j
db.mycoll.count( query = {}, <optional params> ) - count the number of documents that matches the query, optional parameters are: limit, skip, hint, maxTimeMS
db.mycoll.copyTo(newColl) - duplicates collection by copying all documents to newColl; no indexes are copied.
db.mycoll.convertToCapped(maxBytes) - calls {convertToCapped:'mycoll', size:maxBytes}} command
db.mycoll.createIndex(keypattern[,options])
db.mycoll.createIndexes([keypatterns], <options>)
db.mycoll.dataSize()
db.mycoll.deleteOne( filter, <optional params> ) - delete first matching document, optional parameters are: w, wtimeout, j
db.mycoll.deleteMany( filter, <optional params> ) - delete all matching documents, optional parameters are: w, wtimeout, j
db.mycoll.distinct( key, query, <optional params> ) - e.g. db.mycoll.distinct( 'x' ), optional parameters are: maxTimeMS
db.mycoll.drop() drop the collection
db.mycoll.dropIndex(index) - e.g. db.mycoll.dropIndex( "indexName" ) or db.mycoll.dropIndex( { "indexKey" : 1 } )
db.mycoll.dropIndexes()
db.mycoll.ensureIndex(keypattern[,options]) - DEPRECATED, use createIndex() instead
db.mycoll.explain().help() - show explain help
db.mycoll.reIndex()
db.mycoll.find([query],[fields]) - query is an optional query filter. fields is optional set of fields to return.
e.g. db.mycoll.find( {x:77} , {name:1, x:1} )
db.mycoll.find(...).count()
db.mycoll.find(...).limit(n)
db.mycoll.find(...).skip(n)
db.mycoll.find(...).sort(...)
db.mycoll.findOne([query], [fields], [options], [readConcern])
db.mycoll.findOneAndDelete( filter, <optional params> ) - delete first matching document, optional parameters are: projection, sort, maxTimeMS
db.mycoll.findOneAndReplace( filter, replacement, <optional params> ) - replace first matching document, optional parameters are: projection, sort, maxTimeMS, upsert, returnNewDocument
db.mycoll.findOneAndUpdate( filter, update, <optional params> ) - update first matching document, optional parameters are: projection, sort, maxTimeMS, upsert, returnNewDocument
db.mycoll.getDB() get DB object associated with collection
db.mycoll.getPlanCache() get query plan cache associated with collection
db.mycoll.getIndexes()
db.mycoll.group( { key : ..., initial: ..., reduce : ...[, cond: ...] } )
db.mycoll.insert(obj)
db.mycoll.insertOne( obj, <optional params> ) - insert a document, optional parameters are: w, wtimeout, j
db.mycoll.insertMany( [objects], <optional params> ) - insert multiple documents, optional parameters are: w, wtimeout, j
db.mycoll.mapReduce( mapFunction , reduceFunction , <optional params> )
db.mycoll.aggregate( [pipeline], <optional params> ) - performs an aggregation on a collection; returns a cursor
db.mycoll.remove(query)
db.mycoll.replaceOne( filter, replacement, <optional params> ) - replace the first matching document, optional parameters are: upsert, w, wtimeout, j
db.mycoll.renameCollection( newName , <dropTarget> ) renames the collection.
db.mycoll.runCommand( name , <options> ) runs a db command with the given name where the first param is the collection name
db.mycoll.save(obj)
db.mycoll.stats({scale: N, indexDetails: true/false, indexDetailsKey: <index key>, indexDetailsName: <index name>})
db.mycoll.storageSize() - includes free space allocated to this collection
db.mycoll.totalIndexSize() - size in bytes of all the indexes
db.mycoll.totalSize() - storage allocated for all data and indexes
db.mycoll.update( query, object[, upsert_bool, multi_bool] ) - instead of two flags, you can pass an object with fields: upsert, multi
db.mycoll.updateOne( filter, update, <optional params> ) - update the first matching document, optional parameters are: upsert, w, wtimeout, j
db.mycoll.updateMany( filter, update, <optional params> ) - update all matching documents, optional parameters are: upsert, w, wtimeout, j
db.mycoll.validate( <full> ) - SLOW
db.mycoll.getShardVersion() - only for use with sharding
db.mycoll.getShardDistribution() - prints statistics about data distribution in the cluster
db.mycoll.getSplitKeysForChunks( <maxChunkSize> ) - calculates split points over all chunks and returns splitter function
db.mycoll.getWriteConcern() - returns the write concern used for any operations on this collection, inherited from server/db if set
db.mycoll.setWriteConcern( <write concern doc> ) - sets the write concern for writes to the collection
db.mycoll.unsetWriteConcern( <write concern doc> ) - unsets the write concern for writes to the collection
db.mycoll.latencyStats() - display operation latency histograms for this collection
>
> db.test.help() ---db.表名.help()
DBCollection help
db.test.find().help() - show DBCursor help
db.test.bulkWrite( operations, <optional params> ) - bulk execute write operations, optional parameters are: w, wtimeout, j
db.test.count( query = {}, <optional params> ) - count the number of documents that matches the query, optional parameters are: limit, skip, hint, maxTimeMS
db.test.copyTo(newColl) - duplicates collection by copying all documents to newColl; no indexes are copied.
db.test.convertToCapped(maxBytes) - calls {convertToCapped:'test', size:maxBytes}} command
db.test.createIndex(keypattern[,options])
db.test.createIndexes([keypatterns], <options>)
db.test.dataSize()
db.test.deleteOne( filter, <optional params> ) - delete first matching document, optional parameters are: w, wtimeout, j
db.test.deleteMany( filter, <optional params> ) - delete all matching documents, optional parameters are: w, wtimeout, j
db.test.distinct( key, query, <optional params> ) - e.g. db.test.distinct( 'x' ), optional parameters are: maxTimeMS
db.test.drop() drop the collection
db.test.dropIndex(index) - e.g. db.test.dropIndex( "indexName" ) or db.test.dropIndex( { "indexKey" : 1 } )
db.test.dropIndexes()
db.test.ensureIndex(keypattern[,options]) - DEPRECATED, use createIndex() instead
db.test.explain().help() - show explain help
db.test.reIndex()
db.test.find([query],[fields]) - query is an optional query filter. fields is optional set of fields to return.
e.g. db.test.find( {x:77} , {name:1, x:1} )
db.test.find(...).count()
db.test.find(...).limit(n)
db.test.find(...).skip(n)
db.test.find(...).sort(...)
db.test.findOne([query], [fields], [options], [readConcern])
db.test.findOneAndDelete( filter, <optional params> ) - delete first matching document, optional parameters are: projection, sort, maxTimeMS
db.test.findOneAndReplace( filter, replacement, <optional params> ) - replace first matching document, optional parameters are: projection, sort, maxTimeMS, upsert, returnNewDocument
db.test.findOneAndUpdate( filter, update, <optional params> ) - update first matching document, optional parameters are: projection, sort, maxTimeMS, upsert, returnNewDocument
db.test.getDB() get DB object associated with collection
db.test.getPlanCache() get query plan cache associated with collection
db.test.getIndexes()
db.test.group( { key : ..., initial: ..., reduce : ...[, cond: ...] } )
db.test.insert(obj)
db.test.insertOne( obj, <optional params> ) - insert a document, optional parameters are: w, wtimeout, j
db.test.insertMany( [objects], <optional params> ) - insert multiple documents, optional parameters are: w, wtimeout, j
db.test.mapReduce( mapFunction , reduceFunction , <optional params> )
db.test.aggregate( [pipeline], <optional params> ) - performs an aggregation on a collection; returns a cursor
db.test.remove(query)
db.test.replaceOne( filter, replacement, <optional params> ) - replace the first matching document, optional parameters are: upsert, w, wtimeout, j
db.test.renameCollection( newName , <dropTarget> ) renames the collection.
db.test.runCommand( name , <options> ) runs a db command with the given name where the first param is the collection name
db.test.save(obj)
db.test.stats({scale: N, indexDetails: true/false, indexDetailsKey: <index key>, indexDetailsName: <index name>})
db.test.storageSize() - includes free space allocated to this collection
db.test.totalIndexSize() - size in bytes of all the indexes
db.test.totalSize() - storage allocated for all data and indexes
db.test.update( query, object[, upsert_bool, multi_bool] ) - instead of two flags, you can pass an object with fields: upsert, multi
db.test.updateOne( filter, update, <optional params> ) - update the first matching document, optional parameters are: upsert, w, wtimeout, j
db.test.updateMany( filter, update, <optional params> ) - update all matching documents, optional parameters are: upsert, w, wtimeout, j
db.test.validate( <full> ) - SLOW
db.test.getShardVersion() - only for use with sharding
db.test.getShardDistribution() - prints statistics about data distribution in the cluster
db.test.getSplitKeysForChunks( <maxChunkSize> ) - calculates split points over all chunks and returns splitter function
db.test.getWriteConcern() - returns the write concern used for any operations on this collection, inherited from server/db if set
db.test.setWriteConcern( <write concern doc> ) - sets the write concern for writes to the collection
db.test.unsetWriteConcern( <write concern doc> ) - unsets the write concern for writes to the collection
db.test.latencyStats() - display operation latency histograms for this collection
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1.2速查表
| 库操作 | |
| 切换或使用数据库 | use mymongodb |
|---|---|
| 看所有的库 | show dbs |
| 删除当前使用数据库 | db.dropDatabase() |
| 克隆所有的库到当前连接 | db.cloneDatabase(“192.160.1.1”) |
| 复制指定的库 | db.cloneDatabase(“sourcedb”,”targetdb”,”192.168.1.1”) |
| 查看当前数据库 | db.getName() |
| 当前数据库状态 | db.stats() |
| 当前数据库版本 | db.version() |
| 查看当前数据库的连接 | db.getMongo() |
| 用户操作 | |
| 添加用户 | db.addUser(“user_name”, “password”, true) |
| 用户认证 | db.auth(“username”, “password”) |
| 显示所有用户 | show users; |
| 删除用户 | db.removeUser(“username”); |
| 集合基本信息 | |
| 查询集合的数据条数 | db.myCollection.count(); |
| 查看数据空间大小 | db.myCollection.dataSize(); |
| 查看集合所在的数据库 | db.myCollection.getDB(); |
| 当前聚集的状态 | db.myCollection.stats(); |
| 当前集合的总大小 | db.myCollection.totalSize(); |
| 集合储存空间大小 | db.myCollection.storageSize(); |
| Shard版本信息 | db.myCollection.getShardVersion(); |
| 集合重命名 | db.myCollection.renameCollection(“targetCollection”); |
| 删除集合 | db.myCollection.drop(); |
| 集合数据增删改 | |
| 添加记录 | db.myCollection.save({mykey:”t_key”,myvalue:”t-value”}); |
| 删除记录 | db.myCollection.remove({mykey:”t_key”}); |
| 修改记录 | db.myCollection.update({condition: xx}, {$set: {field: ‘changefield’}}, false, true); |
| 查询并修改记录 | db.myCollection.findAndModify(query: {condition1: {gte: XX}}, sort: {condition2: -1}, update: { |
| set: {target1: 'yy'}, $inc: {target2: 2}}, remove: true}); | |
| 集合数据查询 | |
| 查询所有记录 | db.myCollection.find(); |
| 查询第一条记录 | db.myCollection.findOne(); |
| 数据去重 | db.myCollection.distinct(“fieldname”); |
| 数值区间查询 | db.myCollection.find({numfield:{$gte:nn}}); |
| 字符串查询 | db.myCollection.find({targetfield:/ABC/}); |
| 指定字段查询 | db.myCollection.find({},{field1:’abc’,field2:nnn}); |
| 指定返回条数查询 | db.myCollection.find().limit(m).skip(n); |
| 排序 | db.myCollection.find().sort({targetfield:-1}); //降序 |
| 统计记录数 | db.myCollection.find({target: n }).count(); |
| 索引操作 | |
| 创建 | db.myCollection.ensureIndex({targetfield: 1}); |
| 查询所有索引 | db.myCollection.getIndexes(); |
| 查询所有索引大小 | db.myCollection.totalIndexSize(); |
| 查询索引信息 | db.myCollection.reIndex({targetfield: 1}); |
| 删除指定索引 | db.myCollection.dropIndex(“targetfield”); |
| 删除所有索引 | db.myCollection.dropIndexes(); |
| 辅助命令 | |
| 查询错误信息 | db.getPrevError(); |
| 清空错误信息 | db.resetError(); |
| 各种帮助信息 | help; db.help();db.myCollection.help();db.myCollection.find().help();rs.help(); |
1.3基本命令
1）show dbs显示当前数据库服务器上的数据库
2）use pagedb切换到指定数据库pagedb的上下文，可以在此上下文中管理pagedb数据库以及其中的集合等
3）show collections显示数据库中所有的集合（collection）
4）db.serverStatus() 查看数据库服务器的状态。有时，通过查看数据库服务器的状态，可以判断数据库是否存在问题，如果有问题，如数据损坏，可以及时执行修复。
5）查询指定数据库统计信息use fragment db.stats()查询结果示例如下所示：
> use fragment switched to db fragment > db.stats() { "db" : "fragment", "collections" : 0, "objects" : 0, "avgObjSize" : 0, "dataSize" : 0, "storageSize" : 0, "numExtents" : 0, "indexes" : 0, "indexSize" : 0, "fileSize" : 0, "ok" : 1 }
6）查询指定数据库包含的集合名称列表db.getCollectionNames()结果如下所示：
> db.getCollectionNames() [ "17u", "baseSe", "bytravel", "daodao", "go2eu", "lotour", "lvping", "mafengwo", "sina", "sohu", "system.indexes" ]
1.4基本DDL和DML
1）创建数据库如果你习惯了关系型数据库，你可能会寻找相关的创建数据库的命令。在MongoDB中，你可以直接通过use dbname来切换到这个数据库上下文下面，系统会自动延迟创建该数据库，例如：
> show dbs local 0.078GB > use LuceneIndexDB switched to db LuceneIndexDB > show dbs local 0.078GB > db LuceneIndexDB > db.storeCollection.save({'version':'3.5', 'segment':'e3ol6'}) WriteResult({ "nInserted" : 1 }) > show dbs LuceneIndexDB 0.078GB local 0.078GB >
可见，在use指定数据库后，并且向指定其中的一个集合并插入数据后，数据库和集合都被创建了。
2）删除数据库直接使用db.dropDatabase()即可删除数据库。
3）创建集合可以使用命令db.createCollection(name, { size : ..., capped : ..., max : ... } )创建集合，示例如下所示：
> db.createCollection('replicationColletion', {'capped':true, 'size':10240, 'max':17855200}) { "ok" : 1 } > show collections replicationColletion storeCollection system.indexes
4）删除集合删除集合，可以执行db.mycoll.drop()。
5）插入更新记录直接使用集合的save方法，如下所示：
> db.storeCollection.save({'version':'3.5', 'segment':'e3ol6'}) WriteResult({ "nInserted" : 1 })
更新记录，使用save会将原来的记录值进行覆盖实现记录更新。
6）查询一条记录使用findOne()函数，参数为查询条件，可选，系统会随机查询获取到满足条件的一条记录（如果存在查询结果数量大于等于1）示例如下所示：
> db.storeCollection.findOne({'version':'3.5'}) { "_id" : ObjectId("5a4c1733f5c45f057ae82292"), "version" : "3.5", "segment" : "e3ol6" }
7）查询多条记录使用find()函数，参数指定查询条件，不指定条件则查询全部记录。
8）删除记录使用集合的remove()方法，参数指定为查询条件，示例如下所示：
> db.storeCollection.remove({'version':'3.5'}) WriteResult({ "nRemoved" : 2 }) > db.storeCollection.findOne() null
9）创建索引可以使用集合的ensureIndex(keypattern[,options])方法，示例如下所示：
> use pagedb switched to db pagedb > db.page.ensureIndex({'title':1, 'url':-1}) { "createdCollectionAutomatically" : true, "numIndexesBefore" : 1, "numIndexesAfter" : 2, "ok" : 1 } > db.system.indexes.find() { "v" : 1, "key" : { "_id" : 1 }, "name" : "_id_", "ns" : "pagedb.page" } { "v" : 1, "key" : { "title" : 1, "url" : -1 }, "name" : "title_1_url_-1", "ns" : "pagedb.page" }
上述，ensureIndex方法参数中，数字1表示升序，-1表示降序。使用db.system.indexes.find()可以查询全部索引。
10）查询索引我们为集合建立的索引，那么可以通过集合的getIndexes()方法实现查询，示例如下所示：
> db.page.getIndexes() [ { "v" : 1, "key" : { "_id" : 1 }, "name" : "_id_", "ns" : "pagedb.page" }, { "v" : 1, "key" : { "title" : 1, "url" : -1 }, "name" : "title_1_url_-1", "ns" : "pagedb.page" } ]
当然，如果需要查询系统中全部的索引，可以使用db.system.indexes.find()函数。
11）删除索引删除索引给出了两个方法：
> db.mycoll.dropIndex(name) 2018-01-02T23:45:50.155+0000 E QUERY ReferenceError: name is not defined at (shell):1:21 > db.mycoll.dropIndexes() { "ok" : 0, "errmsg" : "ns not found" } >
第一个通过指定索引名称，第二个删除指定集合的全部索引。
12）索引重建可以通过集合的reIndex()方法进行索引的重建，示例如下所示：
> db.page.reIndex() { "nIndexesWas" : 2, "nIndexes" : 2, "indexes" : [ { "key" : { "_id" : 1 }, "name" : "_id_", "ns" : "pagedb.page" }, { "key" : { "title" : 1, "url" : -1 }, "name" : "title_1_url_-1", "ns" : "pagedb.page" } ], "ok" : 1 }
13）统计集合记录数
> use fragment switched to db fragment > db.baseSe.count() 36749
上述统计了数据库fragment的baseSe集合中记录数。
14）查询并统计结果记录数
> use fragment switched to db fragment > db.baseSe.find().count() 36749
find()可以提供查询参数，然后查询并统计结果。上述执行先根据查询条件查询结果，然后统计了查询数据库fragment的baseSe结果记录集合中记录数。
15）查询指定数据库的集合当前可用的存储空间
> use fragment switched to db fragment > db.baseSe.storageSize() 142564096
16）查询指定数据库的集合分配的存储空间
> db.baseSe.totalSize() 144096000
上述查询结果中，包括为集合（数据及其索引存储）分配的存储空间。
1.5安全管理
1）以安全认证模式启动[root@centos6-vm01 ~]# mongod --auth --dbpath /usr/mongo/data --logfile /var/mongo.log使用--auth选项启动mongod进程即可启用认证模式。或者，也可以修改/etc/mongodb.conf，设置auth=true，重启mongod进程。
2）添加用户> db.createUser({user: "admin",pwd: "1234!@#$qwer",roles: [ "readWrite", "dbAdmin" ]})添加数据库用户，添加成功，则显示结果如下所示：
> db.createUser({user: "admin",pwd: "1234!@#$qwer",roles: [ "readWrite", "dbAdmin" ]}) Successfully added user: { "user" : "admin", "roles" : [ "readWrite", "dbAdmin" ] }
3）安全认证前提是必须进入该用户对应的database才行,出现1代表成功> db.auth("admin", "1234!@#$qwer")数据库安全认证。认证成功显示结果：
> use admin switched to db admin > db.auth("admin", "1234!@#$qwer") 1
如果是认证用户，执行某些命令，可以看到正确执行结果，如下所示：
> db.system.users.find() { "_id" : "fragment.admin", "user" : "admin", "db" : "fragment", "credentials" : { "SCRAM-SHA-1" : { "iterationCount" : 10000, "salt" : "/QZtFAvcavqZIm15FmbToA==", "storedKey" : "t91XZuIrnUYtuN1bG+hNg58R+w0=", "serverKey" : "vZLGW0nVpGSKfUHsS2RABOXhOb4=" } }, "roles" : [ { "role" : "readWrite", "db" : "fragment" }, { "role" : "dbAdmin", "db" : "fragment" } ] }
4、为数据库写数据（同步到磁盘）加锁> db.runCommand({fsync:1,lock:1})说明：该操作已经对数据库上锁，不允许执行写数据操作，一般在执行数据库备份时有用。执行命令，结果示例如下：
> db.runCommand({fsync:1,lock:1}) { "info" : "now locked against writes, use db.fsyncUnlock() to unlock", "seeAlso" : "http://dochub.mongodb.org/core/fsynccommand", "ok" : 1 }
5）查看当前锁状态> db.currentOp()说明：查询结果如下所示：
> db.currentOp() { "inprog" : [ ], "fsyncLock" : true, "info" : "use db.fsyncUnlock() to terminate the fsync write/snapshot lock" }
其中，fsyncLock为1表示MongoDB的fsync进程（负责将写入改变同步到磁盘）不允许其他进程执行写数据操作
6）解锁> use admin> db.$cmd.sys.unlock.findOne()说明：执行解锁，结果如下所示：
> use admin switched to db admin > db.$cmd.sys.unlock.findOne() { "ok" : 1, "info" : "unlock completed" }
可以执行命令查看锁状态：db.currentOp()状态信息如下：
> db.currentOp() { "inprog" : [ ] }
说明当前没有锁，可以执行写数据操作。
1.6据备份、恢复与迁移管理
1）备份全部数据库[root@centos6-vm01 ~]# mkdir testbak[root@centos6-vm01 ~]# cd testbak[root@centos6-vm01 ~]# mongodump说明：默认备份目录及数据文件格式为./dump/[databasename]/[collectionname].bson
2）备份指定数据库[root@centos6-vm01 ~]# mongodump -d pagedb说明：备份数据库pagedb中的数据。
3）备份一个数据库中的某个集合[root@centos6-vm01 ~]# mongodump -d pagedb -c page说明：备份数据库pagedb的page集合。
4）恢复全部数据库[root@centos6-vm01 ~]# cd testbak[root@centos6-vm01 ~]# mongorestore --drop说明：将备份的所有数据库恢复到数据库，--drop指定恢复数据之前删除原来数据库数据，否则会造成回复后的数据中数据重复。
5）恢复某个数据库的数据[root@centos6-vm01 ~]# cd testbak[root@centos6-vm01 ~]# mongorestore -d pagedb --drop说明：将备份的pagedb的数据恢复到数据库。
6）恢复某个数据库的某个集合的数据[root@centos6-vm01 ~]# cd testbak[root@centos6-vm01 ~]# mongorestore -d pagedb -c page --drop说明：将备份的pagedb的的page集合的数据恢复到数据库。
7）向MongoDB导入数据[root@centos6-vm01 ~]# mongoimport -d pagedb -c page --type csv --headerline --drop < csvORtsvFile.csv说明：将文件csvORtsvFile.csv的数据导入到pagedb数据库的page集合中，使用cvs或tsv文件的列名作为集合的列名。
需要注意的是，使用--headerline选项时，只支持csv和tsv文件。--type支持的类型有三个：csv、tsv、json其他各个选项的使用，可以查看帮助：
[root@centos6-vm01 ~]# mongoimport --help Usage: mongoimport <options> <file> Import CSV, TSV or JSON data into MongoDB. If no file is provided, mongoimport reads from stdin. See http://docs.mongodb.org/manual/reference/program/mongoimport/ for more information. general options: --help print usage --version print the tool version and exit verbosity options: -v, --verbose more detailed log output (include multiple times for more verbosity, e.g. -vvvvv) --quiet hide all log output connection options: -h, --host= mongodb host to connect to (setname/host1,host2 for replica sets) --port= server port (can also use --host hostname:port) authentication options: -u, --username= username for authentication -p, --password= password for authentication --authenticationDatabase= database that holds the user's credentials --authenticationMechanism= authentication mechanism to use namespace options: -d, --db= database to use -c, --collection= collection to use input options: -f, --fields= comma separated list of field names, e.g. -f name,age --fieldFile= file with field names - 1 per line --file= file to import from; if not specified, stdin is used --headerline use first line in input source as the field list (CSV and TSV only) --jsonArray treat input source as a JSON array --type= input format to import: json, csv, or tsv (defaults to 'json') ingest options: --drop drop collection before inserting documents --ignoreBlanks ignore fields with empty values in CSV and TSV --maintainInsertionOrder insert documents in the order of their appearance in the input source -j, --numInsertionWorkers= number of insert operations to run concurrently (defaults to 1) --stopOnError stop importing at first insert/upsert error --upsert insert or update objects that already exist --upsertFields= comma-separated fields for the query part of the upsert --writeConcern= write concern options e.g. --writeConcern majority, --writeConcern '{w: 3, wtimeout: 500, fsync: true, j: true}' (defaults to 'majority')
8）从向MongoDB导出数据[root@centos6-vm01 ~]# mongoexport -d pagedb -c page -q {} -f _id,title,url,spiderName,pubDate --csv > pages.csv
说明：将pagedb数据库中page集合的数据导出到pages.csv文件，其中各选项含义：-f 指定cvs列名为_id,title,url,spiderName,pubDate-q 指定查询条件其他各个选项的使用，可以查看帮助：
[root@centos6-vm01 ~]# mongoexport --help Usage: mongoexport <options> Export data from MongoDB in CSV or JSON format. See http://docs.mongodb.org/manual/reference/program/mongoexport/ for more information. general options: --help print usage --version print the tool version and exit verbosity options: -v, --verbose more detailed log output (include multiple times for more verbosity, e.g. -vvvvv) --quiet hide all log output connection options: -h, --host= mongodb host to connect to (setname/host1,host2 for replica sets) --port= server port (can also use --host hostname:port) authentication options: -u, --username= username for authentication -p, --password= password for authentication --authenticationDatabase= database that holds the user's credentials --authenticationMechanism= authentication mechanism to use namespace options: -d, --db= database to use -c, --collection= collection to use output options: -f, --fields= comma separated list of field names (required for exporting CSV) e.g. -f "name,age" --fieldFile= file with field names - 1 per line --type= the output format, either json or csv (defaults to 'json') -o, --out= output file; if not specified, stdout is used --jsonArray output to a JSON array rather than one object per line --pretty output JSON formatted to be human-readable querying options: -q, --query= query filter, as a JSON string, e.g., '{x:{$gt:1}}' -k, --slaveOk allow secondary reads if available (default true) --forceTableScan force a table scan (do not use $snapshot) --skip= number of documents to skip --limit= limit the number of documents to export --sort= sort order, as a JSON string, e.g. '{x:1}'
注意：如果上面的选项-q指定一个查询条件，需要使用单引号括起来，如下所示：
[root@centos6-vm01 ~]# mongoexport -d page -c Article -q '{"spiderName": "mafengwoSpider"}' -f _id,title,content,images,publishDate,spiderName,url --jsonArray > mafengwoArticle.txt 2018-01-03T08:12:41.234+0800 connected to: localhost 2018-01-03T08:12:41.234+0800 exported 0 records [root@centos6-vm01 ~]# ll mafengwoArticle.txt -rw-r--r--. 1 root root 3 Jan 3 00:12 mafengwoArticle.txt
否则，就会出现下面的错误：
ERROR: too many positional options
1.7远程连接管理
1）基于mongo实现远程连接[root@centos6-vm01 ~]# mongo 192.168.10.220:27017/pagedb或者[root@centos6-vm01 ~]# mongo 192.168.10.220:27017/pagedb -ukevin -p123456kevin
通过mongo实现连接，可以非常灵活的选择参数选项，参看命令帮助，如下所示：
[root@centos6-vm01 ~]# mongo --help MongoDB shell version: 3.0.6 usage: mongo [options] [db address] [file names (ending in .js)] db address can be: foo foo database on local machine 192.169.0.5/foo foo database on 192.168.0.5 machine 192.169.0.5:9999/foo foo database on 192.168.0.5 machine on port 9999 Options: --shell run the shell after executing files --nodb don't connect to mongod on startup - no 'db address' arg expected --norc will not run the ".mongorc.js" file on start up --quiet be less chatty --port arg port to connect to --host arg server to connect to --eval arg evaluate javascript -h [ --help ] show this usage information --version show version information --verbose increase verbosity --ipv6 enable IPv6 support (disabled by default) Authentication Options: -u [ --username ] arg username for authentication -p [ --password ] arg password for authentication --authenticationDatabase arg user source (defaults to dbname) --authenticationMechanism arg authentication mechanism --gssapiServiceName arg (=mongodb) Service name to use when authenticating using GSSAPI/Kerberos --gssapiHostName arg Remote host name to use for purpose of GSSAPI/Kerberos authentication file names: a list of files to run. files have to end in .js and will exit after unless --shell is specified
2）基于MongoDB支持的javascript实现远程连接当你已经连接到一个远程的MongoDB数据库服务器（例如，通过mongo连接到192.168.0.184），现在想要在这个会话中连接另一个远程的数据库服务器（192.168.0.197），可以执行如下命令：
> var x = new Mongo('192.168.10.220:27017') > var ydb = x.getDB('pagedb'); > use ydb switched to db ydb > db ydb > ydb.page.findOne() { "_id" : ObjectId("4eded6a5bf3bfa0014000003"), "content" : "巴黎是浪漫的城市，可是...", "pubdate" : "2006-03-19", "title" : "巴黎：从布鲁塞尔赶到巴黎", "url" : "http://france.bytravel.cn/Scenery/528/cblsegdbl.html" }
上述通过MongoDB提供的JavaScript脚本，实现对另一个远程数据库服务器进行连接，操作指定数据库pagedb的page集合。
如果启用了安全认证模式，可以在获取数据库连接实例时，指定认证账号，例如：
> var x = new Mongo('192.168.0.197:27017') > var ydb = x.getDB('pagedb', 'shirdrn', '(jkfFS$343$_\=\,.F@3'); > use ydb switched to db ydb