There are many SQL databases so far.But i personally feel the 15 years history of SQL coming to an end as everyone is moving to an era of BigData . As experts say SQL databases are not a best fit for Big Data No Sql databases came into picture as a best fit for this which provides more flexibility in storing data. I just want to compare few popular NoSql databases that are available at this point of time.Few well known NoSql databases are MongoDb Cassandra Hbase CouchDb Neo4j NoSql databases differ each other more than the way Sql databases differ from each other.I think its one's responsibility to choose the appropriate NoSql database for their application based on their use case.Lets do a quick comparison of these databases. MongoDb Written in : c++ Main point : Retains some friendly properties of SQL (Query, Index) Licence : AGPL(Drivers : Apache) Protocol : BSON (Binary JSON) Replication : Master/Slave Replication and automatic failover via Replica Se