MongoDB is an open-source document database. It is developed in C++ and hence, it provides flexibility with object-oriented concepts
MongoDB provides MapReduce VPI’s. There is a tool called Gird FS which is used to store huge amount of data comprising different structure
Schema less is big advantage of MongoDB over RDBMS . one collection holds any no of documents but remember that the maximum document size is 16mb. Number of fields, content and size of the document can be differ from one document to another document.
Advantages of Mongo DB:
• Schema-less – This is perfect for flexible data model altering. In MongoDB, It is easy to declare, extend and alter extra fields to the data model, and optional nulled fields. Using RDBMS databases one must run scripts primarily in order to update the model. In this case it can be done through coding and no scripting is needed.
• Clear structure of a single object – The structure of the model is in ‘Json’ and the structure is clear instead of deriving it from a table structure.
• No SQL or hibernate queries – The good thing about MongoDB is that the operations are not complex to use (without SQL) and are key / value based. Easy expression language operators like ‘$gt’, ‘$lt’ can be used and practise of indexes & cursors is possible.
• Tuning – The level of consistency can be chosen depending on the value of the data.
• Effortlessness scale-out – Scale reads using replica sets and writes using sharding (auto balancing). Just start up another machine and you are good to go. Here, adding more machines distributes your work.
• Scaling – MongoDB also makes it easy to scale out your database. Auto-sharding lets you to scale your cluster linearly by adding more machines, making it possible to increase capacity without any downtime.
• Conversion or mapping of application objects to database objects are not needed.
• Fast Access – Utilizes internal memory for storing working set, allowing faster access to data.
• Ease of use – MongoDB concentrates on being easy to install, configure, maintain and use. For this, MongoDB provides a couple of configuration options and automatically tries to do the correct thing. This allows the user to work right away instead of spending a lot of time in fine tuning obscure database configurations.