MongoDB over view

                                                                     MongoDB

         * MongoDB is   an open-source leading NoSQL database.

         * MongoDB is developed using  C++ .

          * MongoDB works on concept of collection and document i.e MongoDB is a cross-platform

             ,document oriented database  that provides high performance, high availability and easy

             scalability.

Understanding the basic terminologies in MongoDB over RDBMS.

      * Collection in MongoDB is nothing but table in RDBMS.

      * Document in MongoDB is nothing but Touple / Row in RDBMS.

      * Field in MongoDB is nothing but Column in RDBMS.

      * Embedded Documents in MongoDB is nothing but Join in RDBMS.

      * Primary Key (Default key _id provided by mongodb itself) in MongoDB is nothing                                                

         but Primary Key in RDBMS.

     

Note:

          _id is a 12 bytes hexadecimal number uniquely assigned for ever document by mongodb itself .

          First 4 bytes for  the current timestamp, next 3 bytes for  Mechine id , next 2 bytes for Process             id and remaining 3 bytes are simple incremental value. We can also provide the value for _id .