From the hp: “MongoDB (from “humongous”) is a scalable, high-performance, open source NoSQL database. Written in C++, features”

• Document-Oriented Storage (JSON-style documents with dynamic schemas offer simplicity and power)
• Full Index Support (Index on any attribute)
• Replication & High Availability (Mirror across LANs and WANs)
• Auto-Sharding (Scale horizontally without compromising functionality)
• Querying
• Fast In-Place Updates
• Map/Reduce
• GridFS
• Commercial Support

This page aims to be a MongoDB “hello world” example, for more info read

• MongoDBCookBook
• MongoDBAdmin

MongoDB does not support transactions. Atomic operations are supported.

sudo apt-get install mongodb

will pull in all dependencies, install and start the database.

If required, adjust settings in /etc/mongodb.conf (like IP binding or port)

sudo service mongodb stop
sudo service mongodb start

An easy way is the mongo interactive shell. In a terminal, type

mongo

This connects to database “test”.

The information below comes from the MongoDB manual

To use a specific database, say “accounts”, login to mongo and issue

>use accounts

If database “accounts” does not exist yet, it will be created.

List all existing databases:

>show dbs

MongoDB collections can be compared to RDBS tables. Collections are named groupings of documents.

Login to a specific database and list existing collections:

>use accounts
>show collections

As with databases, the first time you access a collection, it will be automatically be created for you.

As mentioned before, MongoDB is document-oriented. Whereas you think of rows in RDBMS, you think of documents in MongoDB. More specifically, MongoDB documents are in JSON format.

Insert one document

> db.transactions.save({"name":"alice","type":"withdrawal", "amount": 30})

or bulk insert (supported in shell since v2.2)

>db.transactions.save([{"name":"alice","type":"deposit", "amount": 500}, {"name":"alice","type":"withdrawal", "amount": 50}, {"name":"bob","type":"withdrawal", "amount": 20}, {"name":"bob","type":"withdrawal", "amount": 60}])

Change transaction type to “deposit” where name=bob and amount 60

> db.transactions.update({"name":"bob", "amount":60}, {$set : {"type":"deposit"}})

db.transactions.drop() 	//drop the entire transactions collection
db.transactions.remove() //remove all objects from the collection
db.transactions.remove( { name : "sara" } )  //remove objects from the collection where name is sara

Get all documents

> db.transactions.find()

Alice's money transactions:

> db.transactions.find({"name" : "alice"})

Show only type and amount fields

> db.transactions.find({}, {"type":true, "amount":true, "_id":false})

> db.transactions.find({}, {}).limit(2)

sort by name ascending, amount descending

> db.transactions.find( {},{}).sort({"name":1,"amount":-1})

Run ensureIndex(), which builds the index ONLY if it does not already exist.

db.transactions.ensureIndex({"name":true});

View existing indizes

db.transactions.getIndexes()

The manual has more details.

> db.transactions.count() 
// or with a WHERE clause
> db.transactions.count({"name":"alice"}) 

How much did all users withdraw?

> db.transactions.group( {
   "key": {"name":true} , 
   "cond": {"type":"withdrawal"}, 
   "reduce": function (obj,prev) { prev.csum += obj.amount; }, 
   "initial": { csum: 0 } 
}  )

> db.transactions.distinct("name")

Use explain() to get statistics about a query, e.g. check “millis” for the query runtime in milliseconds.

NOTE: during the execution of explain(), the actual query is being run! So if the query takes lots of time, explain() will take a long time, too.

> db.transactions.find({},{"name":true, "amount":"true"}).explain()
 
 
{
	"cursor" : "BasicCursor",
	"isMultiKey" : false,
	"n" : 6,
	"nscannedObjects" : 6,
	"nscanned" : 6,
	"nscannedObjectsAllPlans" : 6,
	"nscannedAllPlans" : 6,
	"scanAndOrder" : false,
	"indexOnly" : false,
	"nYields" : 0,
	"nChunkSkips" : 0,
	"millis" : 0,
	"indexBounds" : {
 
	},
	"server" : "ankh:27017"
}