No SQL

Categories of NoSQL Database 

    Key-Value Stores :   This is simplest and fastest in NoSQL 

           Eg : Redis, Memcached, Coherence
    Wide Column Stores(Tabular) :  Due to normalization we will see performance issue in RDBMS .  

                                                          When we use  joins the select queries will be slow.

        Eg:   HBase, Cassandra,Big Table
    Graph Store :    To show the hierarchy this will be used like employee hierarchy in an organization to 

                                 fetch this in RDBMS it going to be a costly Query as it use self join to the same table

        Eg: Neo4J , HyperGraphDB, Oracle NoSQL
    Document Base : Special type of formatted string like JSON. In JSON format we have Key value

        Eg:   Mongodb, CouchDB, cloudant

https://db-engines.com/en/ranking/key-value+store

Entity	SQL databases	NoSQL Databases
Type	One Type(SQL) with Minor Variation	Many Types(Document,Key-value,Tabular,Graph)
Development	1970	2000
Examples	Oracle, SSQL, DB2 etc	MongoDB,Cassandra, Hbase, Neo4J
Schema	Fixed	Dynamic
Scaling	Vertical	Horizontal
Dev Model	Mix	Open source
Consistency	Follow ACID	Follow BASE

ACID - Atomic, Consistent,Isolated, Durable

CAP Theorem -  Consistency , Availability , Partition Tolerance

CA (Consistency and Availability) : RDMS (Oracle,MySQL,MircoosftSQL,DB2)

CP (Consistency and Partition Tolerance) : Mongodb, HBase, Redis

AP(Availability, Partition Tolerance ): CouchDB, Cassandra,DynamoDB,Riak

BASE  : Basiclly Available, Soft State, Eventual Consistency