Introduction to Mongo DB

Mongo DB is an open source document-oriented No SQL database system.

No SQL Database System

1. It does not use SQL as its query language.

2. It may not give full ACID guarantees.

RDBMS vs. Mongo

Mongo DB data model

1. Mongo system: Collection of databases.

2. Database: Set of collections.

3. Collection: Set of documents.

4. Document: Set of fields.

5. Field: Key-Value pair.

· Key : Name (String).

· Value : String, integer, float, timestamp, binary, document, Array of values.

Mongo DB Basic Components

1. Database Server : mongod.exe

2. Interactive Shell : mongo.exe

3. Sharding Router : mongos.exe

JSON

It stands for JavaScript Object Notation.

Example:

{ _id : "109",name : "hemant kumar", hobbies : [ ”chess",”comics" ] }

BSON

· It stands for Binary JSON.

· BSON is a binary representation of JSON

· Mongo DB stores data in BSON

Documents

Mongo DB is a document based database. This means that we store data as documents.

Sample documents in Interactive shell with its equivalent code in java.

var a = {name: "Hemant Kumar"}

BasicDBObject obj = new BasicDBObject("name","Hemant Kumar");

var n = {name: 'Hemant Kumar', languages: ['c', ‘mongodb’, 'java']}

BasicDBObject obj = new BasicDBObject("name","Hemant Kumar");

ArrayList<String> list = new ArrayList<String>();

list.add("c");

list.add("mongodb");

list.add("java");

obj.append("languages",list);

var t = { name:'Hemant Kumar', info: { lang:['c', ‘mongodb’, 'java'] } }

BasicDBObject obj = new BasicDBObject("name","Hemant Kumar");

ArrayList<String> list = new ArrayList<String>();

list.add("c");

list.add("mongodb");

list.add("java");

obj.append("info",new BasicDBObject("lang",list));

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