The advantages of Key Value Databases are their high performance and flexible scalability, both of which stem from the model’s simple structure. As Key Value Stores don’t require or stipulate any uniform pattern, changes to the database can be made while in operation. It’s possible to introduce a new field while actions are happening in other entries at the same time.
The high speed makes this database model possible through the simple connection of key and value. If you want to retrieve information, you simply access the value directly via its specific key. The data is available directly. At the same time, though, this is a disadvantage of the Key Value Store, as no other access method is available. Relational databases permit complex queries. The content of such databases can be sifted through in various aspects. In contrast, a Key Value Store only allows for access via the key. It’s generally necessary to do without further indices and search possibilities.
The applications of Key Value Stores are based on both their advantages and their restrictions. Key Value Databases are used whenever quick access times are needed for large quantities of data. For this reason, typical applications are shopping carts in online shops, or session data. Here, information is clearly ordered and must be available in the shortest possible time. For large, well-known websites, these databases must constantly create new entries and delete old ones, something that Key Value Databases are perfectly adapted to.