本次環境 RHEL6

學著用一下MongoDB，做個筆記：

下載&安裝

預建立datadir和logdir

編輯配置檔案

可以最簡化的寫一下配置，其他的預設

儲存退出

啟動mongodb

進入mongodb shell

或者不加選項直接：

MongoDB shell version: 3.2.10
connecting to: test
Server has startup warnings:
2016-10-03T12:38:14.769+0800 I CONTROL [initandlisten] ** WARNING: You are running this process as the root user, which is not recommended.
2016-10-03T12:38:14.769+0800 I CONTROL [initandlisten]
2016-10-03T12:38:14.769+0800 I CONTROL [initandlisten]
2016-10-03T12:38:14.769+0800 I CONTROL [initandlisten] ** WARNING: /sys/kernel/mm/transparent_hugepage/enabled is 'always'.
2016-10-03T12:38:14.769+0800 I CONTROL [initandlisten] ** We suggest setting it to 'never'
2016-10-03T12:38:14.774+0800 I CONTROL [initandlisten]
2016-10-03T12:38:14.774+0800 I CONTROL [initandlisten] ** WARNING: /sys/kernel/mm/transparent_hugepage/defrag is 'always'.
2016-10-03T12:38:14.774+0800 I CONTROL [initandlisten] ** We suggest setting it to 'never'
2016-10-03T12:38:14.774+0800 I CONTROL [initandlisten]
>

這三個wanring，後兩個可以透過修改如下檔案，來關閉transparent_hugepage

但這樣重啟會被重置成always，可以寫個指令碼或者放入/etc/rc.local中

關閉hugepage之後，重啟mongd，進入mongo shell則該warning消失：

shell> mongo
MongoDB shell version: 3.2.10
connecting to: test
Server has startup warnings:
2016-10-12T05:31:46.933+0800 I CONTROL [initandlisten] ** WARNING: You are running this process as the root user, which is not recommended.
2016-10-12T05:31:46.933+0800 I CONTROL [initandlisten]
>
>

還剩一個warning則很明顯，不建議透過root使用者來啟動mongod。
如果不想讓warning再顯示，可以開啟quiet選項，比如新增到配置檔案中：quiet=true
或者

透過help便可獲取常用mongo shell語法：

> 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

比如查怎麼關閉mongod：
先查db相關的幫助：

> db.help()
………………
db.shutdownServer()
………………
> db.shutdownServer()
server should be down...
2016-10-13T17:58:49.544+0800 I NETWORK [thread1] trying reconnect to 127.0.0.1:27017 (127.0.0.1) failed
2016-10-13T17:58:49.547+0800 I NETWORK [thread1] Socket recv() errno:104 Connection reset by peer 127.0.0.1:27017
2016-10-13T17:58:49.547+0800 I NETWORK [thread1] SocketException: remote: (NONE):0 error: 9001 socket exception [RECV_ERROR] server [127.0.0.1:27017]
2016-10-13T17:58:49.547+0800 I NETWORK [thread1] reconnect 127.0.0.1:27017 (127.0.0.1) failed failed
>

這樣，mongod就已經被關閉了。

【MongoDB】 MongoDB 3.2.x 安裝實踐

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