MongoDB的命令帮助系统（四）

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。看一下MongoDB的命令帮助系统：

root@dev2:~# mongo  
MongoDB shell version: 1.8.3  
connecting to: test  
> help  
        db.help()                    help on db methods  
        db.mycoll.help()             help on collection methods  
        rs.help()                    help on replica set methods  
        help connect                 connecting to a db help  
        help admin                   administrative help  
        help misc                    misc things to know  
        help mr                      mapreduce help  
  
        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  
        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.addUser(username, password[, readOnly=false])  
        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.currentOp() displays the current operation in the db  
        db.dropDatabase()  
        db.eval(func, args) run code server-side  
        db.getCollection(cname) same as db['cname'] or db.cname  
        db.getCollectionNames()  
        db.getLastError() - just returns the err msg string  
        db.getLastErrorObj() - return full status object  
        db.getMongo() get the server connection object  
        db.getMongo().setSlaveOk() allow this connection to read from the nonmaster member of a replica pair  
        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.isMaster() check replica primary status  
        db.killOp(opid) kills the current operation in the db  
        db.listCommands() lists all the db commands  
        db.printCollectionStats()  
        db.printReplicationInfo()  
        db.printSlaveReplicationInfo()  
        db.printShardingStatus()  
        db.removeUser(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.setProfilingLevel(level,<slowms>) 0=off 1=slow 2=all  
        db.shutdownServer()  
        db.stats()  
        db.version() current version of the server  
        db.getMongo().setSlaveOk() allow queries on a replication slave 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.count()  
        db.mycoll.dataSize()  
        db.mycoll.distinct( key ) - eg. db.mycoll.distinct( 'x' )  
        db.mycoll.drop() drop the collection  
        db.mycoll.dropIndex(name)  
        db.mycoll.dropIndexes()  
        db.mycoll.ensureIndex(keypattern[,options]) - options is an object with these possible fields: name, unique, dropDups  
        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])  
        db.mycoll.findAndModify( { update : ... , remove : bool [, query: {}, sort: {}, 'new': false] } )  
        db.mycoll.getDB() get DB object associated with collection  
        db.mycoll.getIndexes()  
        db.mycoll.group( { key : ..., initial: ..., reduce : ...[, cond: ...] } )  
        db.mycoll.mapReduce( mapFunction , reduceFunction , <optional params> )  
        db.mycoll.remove(query)  
        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()  
        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])  
        db.mycoll.validate() - SLOW  
        db.mycoll.getShardVersion() - only for use with sharding  

 

有关数据库和集合管理的相关命令，是最基础和最常用的，如集合查询、索引操作等。