MongoDB

is a non-relational data store for JSON documents. By non-relational means, it doesn't store its data in tables like a relational database does. It stores data in JSON documents. MongoDB is schemaless, it means that two documents don't need to have the same schema. It is (from "humongous") a scalable, high-performance, open source, document-oriented database.
By default, it stores data in '/data/db'. Default port is 27017.

Mongo Shell

Mongo shell is an administrative shell and has lot of similarities with node.js. It is a C++ program control using V8. Node.js application interact with MongoDB with help of node.js driver.

Features supported

1) indexes
2) secondary indexes

Features not supported

1) Joins
2) Transactions across multiple collections

Standard commands

• db.names.insert()
• db.names.find()
• show dbs (to see the available databases)
• use database_name (to switch or use database)

Download

• Visit http://www.mongodb.org/downloads and choose the appropriate release for your OS

Installation

• Pre-create a user - u: mongouser g: mongo
• Pre-create directory structure for the Mongo Home and the database home
  Eg:
  mkdir /u01/mongodb  - this will be the Mongo install base
  mkdir -p /u01/mongodb/data/db - the main database files
• Unpack the downloaded tarball into the Mongo install base
  Eg:
  cd /u01/mongodb
  tar -xvf mongo-linux-x86_64-2.0.0.tgz
• Move the contents of this back into /u01/mongodb and rm the dir mongo-linux-x86_64-2.0.0.
• Update the .bashrc to reflect the MONGO_HOME and update the PATH
  MONGO_HOME=/u01/mongodb
  export MONGO_HOME
  PATH=$PATH:.:$MONGO_HOME/bin

Start the background process

nohup $MONGO_HOME/bin/mongod --dbpath /u01/mongodb/data/db > /u01/mongodb/mongod.nohup 2>&1 &

Connect to Mongo and connect to a database called jimdb

[mongouser@iadorclgrid02 mongodb]$ mongo
MongoDB shell version: 2.0.0
connecting to: test
> use jimdb
switched to db jimdb

Backup the jimdb database

• Lock the database to prevent writes
  $MONGO_HOME/bin/mongo admin $MONGO_HOME/bin/fsync_lock.js
• Backup the database
  $MONGO_HOME/bin/mongodump -d jimdb  -o /u01/mongodb/dump
• Unlock the database to allow writes again
  $MONGO_HOME/bin/mongo admin $MONGO_HOME/bin/unlock.js

Drop a database and shutdown the server process

• Connect to the chosen database
  MongoDB shell version: 2.0.0
  connecting to: test
  > use jimdb
  switched to db jimdb
• Drop the database
  > db.dropDatabase()
  { "dropped" : "jimdb", "ok" : 1 }
• Connect to the admin database to shutdown a server
  > use admin
  switched to db admin
• Shutdown the Mongo server (NB: this is not the host !)
  > db.shutdownServer()
  Thu Oct 13 11:26:55 DBClientCursor::init call() failed { shutdown: 1.0 }
  Thu Oct 13 11:26:55 query failed : admin.$cmd to: 127.0.0.1 server should be down...
  Thu Oct 13 11:26:55 trying reconnect to 127.0.0.1
  Thu Oct 13 11:26:55 reconnect 127.0.0.1 failed couldn't connect to server 127.0.0.1
  Thu Oct 13 11:26:55 Error: error doing query: unknown shell/collection.js:150

You can tail the mongod.nohup file to see the shutdown messages
Thu Oct 13 11:26:55 dbexit: shutdown called
Thu Oct 13 11:26:55 [conn3] shutdown: going to close listening sockets...
Thu Oct 13 11:26:55 [conn3] closing listening socket: 6
Thu Oct 13 11:26:55 [conn3] closing listening socket: 7
Thu Oct 13 11:26:55 [conn3] closing listening socket: 8
Thu Oct 13 11:26:55 [conn3] removing socket file: /tmp/mongodb-27017.sock
Thu Oct 13 11:26:55 [conn3] shutdown: going to flush diaglog...
Thu Oct 13 11:26:55 [conn3] shutdown: going to close sockets...
Thu Oct 13 11:26:55 [conn3] shutdown: waiting for fs preallocator...
Thu Oct 13 11:26:55 [conn3] shutdown: lock for final commit...
Thu Oct 13 11:26:55 [conn3] shutdown: final commit...
Thu Oct 13 11:26:55 [conn3] shutdown: closing all files...
Thu Oct 13 11:26:55 [conn3] closeAllFiles() finished
Thu Oct 13 11:26:55 [conn3] journalCleanup...
Thu Oct 13 11:26:55 [conn3] removeJournalFiles
Thu Oct 13 11:26:55 [conn3] shutdown: removing fs lock...
Thu Oct 13 11:26:55 dbexit: really exiting now