No Sql Database

A NoSQL database  can be called as  non SQL or non relational  database that provides a way  to  store and retrieve data  modeled in non  tabular format.

Why NoSqL?

A traditional database system    prefers more predictable, structured data  and has been dominating the database industry for the past few years. Nowadays as business grows,social media dominates there is a need  

1.support a large number of  concurrent users

2.Handle huge amount of   semi structured  data as well as unstructured data

3.High availability system without any downtime

4.Huge amount of data insertion and population

Hence , Relational databases are unable to meet these new requirements, and enterprises are therefore turning to NoSQL database technology. 

RDBMS vs No SQL Database

RDBMS	No Sql DBMS
It  is used to process structured data	Its is used for unstructured and semi structured data.
It has fixed schema	It does not have any predefined  schema
It is vertically scalable so to manage the increasing load by increase in CPU, RAM, SSD on a single server.Hence it costs higher	It is horizontally scalable so to handle the large traffic you can add few commodity servers to support that. So it is cost effective
It uses specific language to manipulate data like insert ,update etc	Its is based on object oriented APIs
It follows ACID properties(Atomicity, Consistency, Isolation, Durability).	It folows  Brewers CAP theorem(Consistency, Availability and Partition tolerance).
Example MySql, Oracle, Sqlite, Postgres and MS-SQL.	MongoDB, BigTable, Redis, Cassandra, Hbase, Neo4j  etc are popular No SQL databases.

Types of No Sql database system

four major types of NoSQL databases emerged: document databases, key-value databases, column based database , and graph databases.

Let’s explain each type. 

Document databases:

Document-Oriented NoSQL DB stores and retrieves data as a key value pair but the value part  associated with key is stored as a document. Each document is self-contained, which means no schema is required – giving a significant degree of flexibility over the data you have. 

Amazon SimpleDB, CouchDB, MongoDB,  Lotus Notes are popular Document oriented DBMS systems. 

Key-value databases:

Here data is stored in key/value pairs format ,hence it can handle tons of data and heavy load.

These  are the most basic type of NoSQL database and very  useful for storing fairly basic information, like details about a customer. 

Redis, Dynamo, Riak etc are popular  key-value store Databases .

Column based database:

Column-based databases stored  data into discrete columns instead of using rows.

It doesn’t consume space for a column when its value not exists or null.

Thus it increase speed while querying the data and deliver high performance on aggregation queries like SUM, COUNT, AVG, MIN etc. as the data is readily available in a column. 

Hbase and Cassandra are the examples of  columnar databases .

Graph databases:

A graph database is any storage system that provides index-free adjacency which means that every element contains a direct pointer to its adjacent element and no index lookups are necessary.  

Here storage is in graphical format where node represents data and edge  describes their relationship to other nodes. 

These are  useful for applications ranging from fraud detection to smart homes to search. 

Neo4j, GraphDB etc.  are popular Graph Databases. 

As enterprises  moves  to the Digital Economy  platform driven  by cloud, mobile, social media, and big data technologies – Technical ,operations and development  teams need to focus more in building and maintaining   web, mobile, and Internet of Things (IoT) applications faster at  greater scale. NoSQL is  a demanding  and the preferred database technology to support these applications.