1 固定集合
固定集合值得是事先创建而且大小固定的集合
2 固定集合的特征:固定集合很像环形队列,如果空间不足,最早文档就会被删除,为新的文档腾出空间。一般来说,固定集合适用于任何想要自动淘汰过期属性的场景,没有太多的操作限制。
3 创建固定集合使用命令:
db.createCollection(“collectionName”,{capped:true,size:100000,max:100});
size:指定集合大小,单位为KB,max指定文档的数量
当指定文档数量上限时,必须同时指定大小。淘汰机制只有在容量还没有满时才会依据文档数量来工作。要是容量满了,淘汰机制依据容量来工作。
4 创建一个集合:
>db.createCollection("cap1",{capped:true,size:1000,max:100});
{ "ok" : 1 }
>
5 插入数据
> for(var i=1;i<=100;i++){
...db.cap1.insert({name:"dongxue",age:i});
... }
WriteResult({ "nInserted" : 1 })
> db.cap1.find().count();
53 (大小之所以是53是因为大小超过了1000)
6 固定集合的应用场景:聊天记录,日志信息
淘汰机制:当满足size指定集合大小,不能再继续往固定集合中加数据。
固定集合的容量优先
当文档达到100条时,再添加的时候会替换先前的
7 备份与导入导出。
MongoDB提供了备份和回复的功能,分别是MongoDB下载目录下的mongodump.exe和mongorestore.exe文件。
备份数据使用下面的命令:
mongodump –h dbhost –d dbname –o dbdirectory
-h:MonDB所在服务器地址,例如:127.0.0.1,当然也可以指定端口号:127.0.0.1:27017,当然该目录需要提前创建,在备份完成后,系统自动在dump目录下建立一个test目录,这个目录里面存放该数据库实例的备份数据。
mongodump -h localhost:27017 -d toto -of:/beifeng
-h:用来指定要输出的数据库所在的ip地址和端口号
-d: 指定要备份的数据库
-o: 表示要备份到的文件目录
执行后的效果图:
7 另外启动一个mongodb的客户端,目的是将数据库中toto数据库删掉
C:\Users\to-to>mongo
MongoDB shell version: 2.6.4
connecting to: test
> use toto;
switched to db toto
> db.help();
DB methods:
db.adminCommand(nameOrDocument) - switches to 'admin' db, and runs command [ just calls db.r
unCommand(...) ]
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.createUser(userDocument)
db.currentOp() displays currently executing operations in the db
db.dropDatabase()
db.eval(func, args) run code server-side
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.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 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, inherit
ed 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.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
> db.dropDatabase();
{ "dropped" : "toto", "ok" : 1 }
>
8 数据还原
mongorestore -h localhost:27017 -d toto -directoryperdb F:/beifeng/toto
-h:MongoDB所在服务器地址,例如:127.0.0.1,当然也可以指定端口号:127.0.0.1:27017
-d:需要备份的数据库实例,例如test
-o:备份的数据存放位置,当然该目录需要提前建立,在备份完成后,系统自动在dump目录下建立一个test目录,这个目录里面存放数据库实例的备份数据。
C:\Users\to-to> mongorestore -h localhost:27017 -d toto -directoryperdb F:/beifeng/toto
connected to: localhost:27017
2014-10-15T23:19:11.071+0800 F:/beifeng/toto\c3.bson
2014-10-15T23:19:11.071+0800 going into namespace [toto.c3]
2014-10-15T23:19:14.009+0800 Progress: 5740200/54000000 10% (bytes)
2014-10-15T23:19:17.010+0800 Progress: 10125000/54000000 18% (bytes)
2014-10-15T23:19:20.010+0800 Progress: 15660000/54000000 29% (bytes)
2014-10-15T23:19:23.011+0800 Progress: 22528800/54000000 41% (bytes)
2014-10-15T23:19:26.013+0800 Progress: 29586600/54000000 54% (bytes)
2014-10-15T23:19:29.013+0800 Progress: 36752400/54000000 68% (bytes)
2014-10-15T23:19:32.000+0800 Progress: 43372800/54000000 80% (bytes)
2014-10-15T23:19:35.001+0800 Progress: 50284800/54000000 93% (bytes)
1000000 objects found
2014-10-15T23:19:36.579+0800 Creating index: { key: { _id: 1 }, name: "_id_", ns: "toto.c3" }
2014-10-15T23:19:36.641+0800 Creating index: { unique: true, key: { age: 1 }, name: "age_1", ns:
"toto.c3" }
2014-10-15T23:19:41.440+0800 F:/beifeng/toto\cap1.bson
2014-10-15T23:19:41.440+0800 going into namespace [toto.cap1]
2014-10-15T23:19:41.440+0800 Created collection toto.cap1 with options: { "create" : "cap1", "cap
ped" : true, "size" : 4096, "max" : 100 }
53 objects found
2014-10-15T23:19:41.440+0800 Creating index: { key: { _id: 1 }, name: "_id_", ns: "toto.cap1" }
2014-10-15T23:19:41.440+0800 F:/beifeng/toto\cap2.bson
2014-10-15T23:19:41.440+0800 going into namespace [toto.cap2]
2014-10-15T23:19:41.440+0800 Created collection toto.cap2 with options: { "create" : "cap2", "cap
ped" : true, "size" : 4096, "max" : 100 }
file F:/beifeng/toto\cap2.bson empty, skipping
2014-10-15T23:19:41.456+0800 Creating index: { key: { _id: 1 }, name: "_id_", ns: "toto.cap2" }
C:\Users\to-to>
9 导入导出:
用到的应用mongoexport,mongoimport
mongoexport –h dhost –d dbname –c collectionName –o output
参数说明:
-h 数据库地址
-d 指明使用的库
-c 指明要导出的集合
-o 指明要导出的文件名
dname:表示要导出的数据库
collectionName:表示导出哪个集合
output:表示导出到的位置。
C:\Users\to-to>mongoexport -h localhost:27017 -d toto -c c3 -o f:/beifen/c3.txt
connected to: localhost:27017
exported 1000000 records
C:\Users\to-to>
同样可以数据导出到doc中
数据导入:
mongoimport -h localhost:27017 -d toto -c ccc f:/beifen/c3.txt
C:\Users\to-to>mongo
MongoDB shell version: 2.6.4
connecting to: test
> use toto
switched to db toto
> show tables;
c3
cap1
cap2
ccc
system.indexes
> db.ccc.find();
{ "_id" : ObjectId("543e7473256769913d467e75"), "name" : "zhangsan", "age" : 1 }
{ "_id" : ObjectId("543e7473256769913d467e76"), "name" : "zhangsan", "age" : 2 }
{ "_id" : ObjectId("543e7473256769913d467e77"), "name" : "zhangsan", "age" : 3 }
{ "_id" : ObjectId("543e7473256769913d467e78"), "name" : "zhangsan", "age" : 4 }
{ "_id" : ObjectId("543e7473256769913d467e79"), "name" : "zhangsan", "age" : 5 }
{ "_id" : ObjectId("543e7473256769913d467e7a"), "name" : "zhangsan", "age" : 6 }
{ "_id" : ObjectId("543e7473256769913d467e7b"), "name" : "zhangsan", "age" : 7 }
{ "_id" : ObjectId("543e7473256769913d467e7c"), "name" : "zhangsan", "age" : 8 }
{ "_id" : ObjectId("543e7473256769913d467e7d"), "name" : "zhangsan", "age" : 9 }
{ "_id" : ObjectId("543e7473256769913d467e7e"), "name" : "zhangsan", "age" : 10 }
{ "_id" : ObjectId("543e7473256769913d467e7f"), "name" : "zhangsan", "age" : 11 }
{ "_id" : ObjectId("543e7473256769913d467e80"), "name" : "zhangsan", "age" : 12 }
{ "_id" : ObjectId("543e7473256769913d467e81"), "name" : "zhangsan", "age" : 13 }
{ "_id" : ObjectId("543e7473256769913d467e82"), "name" : "zhangsan", "age" : 14 }
{ "_id" : ObjectId("543e7473256769913d467e83"), "name" : "zhangsan", "age" : 15 }
{ "_id" : ObjectId("543e7473256769913d467e84"), "name" : "zhangsan", "age" : 16 }
{ "_id" : ObjectId("543e7473256769913d467e85"), "name" : "zhangsan", "age" : 17 }
{ "_id" : ObjectId("543e7473256769913d467e86"), "name" : "zhangsan", "age" : 18 }
{ "_id" : ObjectId("543e7473256769913d467e87"), "name" : "zhangsan", "age" : 19 }
{ "_id" : ObjectId("543e7473256769913d467e88"), "name" : "zhangsan", "age" : 20 }
Type "it" for more
>
上面自动隐式创建了一个ccc集合。
9 mongodb安全认证
每个mongodb实例中的数据库都可以有许多用户,如果开启了安全性检查,只有数据库认证用户才能执行读或者写操作。在认证的上下文中,MongoDB会将普通的数据作为admin
数据库处理。Admin数据库中的用户被视为超级用户(即:管理员)
在认证之后,管理员可以读写所有数据库,执行特定的管理员命令,执行listDatabase和shutdown.
在开启安全检查之前,一定要至少一个管理员账号。
-
最少得保证有一个管理员账号(admin 数据库当中的用户都是管理员)
use admin
db.addUser(“username”,”password”);
2.有了管理员账号,就可以为其它的数据库分配用户。
2.1 首先要跳转到被分配的数据库
3.需要重新启动mongodb服务,开启安全检查
4.接下来的客户端连接mongodb,需要登录才能执行相应的操作。
C:\Users\to-to>mongo localhost:27017/admin
MongoDB shell version: 2.6.4
connecting to: localhost:27017/admin
> db
admin