mongodb（一）-入门
参考：
http://www.yiibai.com/mongodb/
http://blog.csdn.net/yuwenruli/article/details/8529192
一、是什么
mongodb是一个跨平台的，面向文档的数据库，提供高性能，高可用性和可扩展性方便。
下面列出RDBMS术语与mongodb的关系：
| Database 数据库 | Database |
| Table 表 | Collection |
| Tuple/Row 行 | Document |
| column 列 | Field |
| Table Join 联表 | Embedded Documents |
| Primary Key 主键 | Primary Key (Default key _id provided by mongodb itself) |
| Mysqld/Oracle | mongod |
| mysql/sqlplus | mongo |
不适用场景：
1、高度事务性系统
2、复杂的跨表级查询
二、安装
1. 下载相应版本的mongodb：mongodb-linux-x86_64-3.0.4
2. 放到任意目录，比如：/home/mongodb-linux-x86_64-3.0.4
3. 新建数据文件夹和日志文件：
[root@www mongodb-linux-x86_64-3.0.4]# mkdir data [root@www mongodb-linux-x86_64-3.0.4]# touch logs三、启动
[root@www home]# cd mongodb-linux-x86_64-3.0.4/bin/ [root@www bin]# ./mongod --dbpath=/home/mongodb-linux-x86_64-3.0.4/data/ --logpath=/home/mongodb-linux-x86_64-3.0.4/logs --logappend --port=27017 --fork about to fork child process, waiting until server is ready for connections. forked process: 4528 child process started successfully, parent exiting参数解释：
--dbpath 数据库路径（数据文件）
--logpath 日志文件路径
--logappend 日志文件末尾增加
--port 启用端口号
> use joan
switched to db joan
> db.dropDatabase()
{ "ok" : 1 }--fork 启用子进程运行
用配置文件来启动：每次启动mongodb时，都要配置如此多参数，是不是有点太麻烦了？我们可以用配置文件来代替。
配置文件内容：
dbpath = /home/mongodb-linux-x86_64-3.0.4/data port = 27017 fork = ture logappend = true logpath = /home/mongodb-linux-x86_64-3.0.4/logs
Last login: Thu Jul 30 06:16:34 2015 [root@www ~]# cd /home/mongodb-linux-x86_64-3.0.4/ [root@www mongodb-linux-x86_64-3.0.4]# mkdir data/mongodb_27017 [root@www mongodb-linux-x86_64-3.0.4]# cd data/mongodb_27017/ [root@www mongodb_27017]# vi mongodb_27017.cnf [root@www mongodb_27017]# cd .. [root@www data]# cd .. [root@www mongodb-linux-x86_64-3.0.4]# cd bin/ [root@www bin]# ./mongod -f /home/mongodb-linux-x86_64-3.0.4/data/mongodb_27017/mongodb_27017.cnf about to fork child process, waiting until server is ready for connections. forked process: 2381 child process started successfully, parent exiting
查看配置文件：
> use admin
switched to db admin
> db.runCommand({getCmdLineOpts:1})
{
"argv" : [
"./mongod",
"-f",
"/home/mongodb-linux-x86_64-3.0.4/data/mongodb_27017/mongodb_27017.cnf"
],
"parsed" : {
"config" : "/home/mongodb-linux-x86_64-3.0.4/data/mongodb_27017/mongodb_27017.cnf",
"net" : {
"port" : 27017
},
"processManagement" : {
"fork" : true
},
"storage" : {
"dbPath" : "/home/mongodb-linux-x86_64-3.0.4/data"
},
"systemLog" : {
"destination" : "file",
"logAppend" : true,
"path" : "/home/mongodb-linux-x86_64-3.0.4/logs"
}
},
"ok" : 1
}四、客户端连接
[root@www bin]# ./mongo MongoDB shell version: 3.0.4 connecting to: test Welcome to the MongoDB shell. For interactive help, type "help". For more comprehensive documentation, see http://docs.mongodb.org/ Questions? Try the support group http://groups.google.com/group/mongodb-user Server has startup warnings: 2015-07-21T19:55:26.318+0800 I STORAGE [initandlisten] 2015-07-21T19:55:26.318+0800 I STORAGE [initandlisten] ** WARNING: Readahead for /home/mongodb-linux-x86_64-3.0.4/data/ is set to 4096KB 2015-07-21T19:55:26.318+0800 I STORAGE [initandlisten] ** We suggest setting it to 256KB (512 sectors) or less 2015-07-21T19:55:26.318+0800 I STORAGE [initandlisten] ** http://dochub.mongodb.org/core/readahead 2015-07-21T19:55:26.551+0800 I CONTROL [initandlisten] ** WARNING: You are running this process as the root user, which is not recommended. 2015-07-21T19:55:26.551+0800 I CONTROL [initandlisten] 2015-07-21T19:55:26.552+0800 I CONTROL [initandlisten] 2015-07-21T19:55:26.552+0800 I CONTROL [initandlisten] ** WARNING: /sys/kernel/mm/transparent_hugepage/enabled is 'always'. 2015-07-21T19:55:26.552+0800 I CONTROL [initandlisten] ** We suggest setting it to 'never' 2015-07-21T19:55:26.552+0800 I CONTROL [initandlisten] >五、关闭