A NoSQL database (originally referred to as "non-SQL" or "non-relational") provides a mechanism for storing and retrieving data that is modeled by means other than the tabular relations used in relational databases. NoSQL databases are increasingly used in big data and real-time web applications. Some popular No-Sql databases include MongoDB, Redis, Couch DB, etc. But the question remains: how to select which No-Sql database for optimal performance according to your needs? Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an Original Essay To debunk the theory about this, let's look at the following points that act as major factors in selecting No-SQL databases: Storage Type A good indicator towards making the right choice for NoSQL database is its type of storage. For example, get, put, and delete functions are best supported by Key Value systems. Aggregation becomes much easier when using column-oriented systems compared to conventional row-oriented databases. They use tables but have no joins. Data mapping becomes easy from object-oriented software using a document-oriented NoSQL database such as XML or JSON as they use structured document formats. Concurrency Control Concurrency control is what defines how two users can simultaneously change the same bit of information. It happens quite often that one of the users gets blocked and is unable to edit or perform any other actions until the active user finishes editing. For example: Please note: this is just an example. Get a custom paper from our expert writers now. Get Custom Essays Locks prevent more than one active user from modifying an entity such as a document, row, or object. MVCC (Multi-Version Concurrency Control) ensures a consistent view when reading the database, but causes conflicting versions of an entity if multiple users modify it at the same time. MVCC makes it possible for a transaction to run smoothly by maintaining many different versions of the object. Replication Replication ensures that mirror copies are always synchronized. Synchronous mode: Although it is an expensive approach as there is a dependency on the second server to respond, but it always ensures consistency. After receiving the response from the second server, the first server returns the ACK to the client. This ensures that data is inserted into multiple nodes at the same time. Asynchronous mode: In this mode, a database is updated without waiting for the response from the other database. Two databases may not be consistent within a few milliseconds.