What are the main categories of NOSQL systems? List a few of the NOSQL systems.
Types of NoSQL Databases Several different varieties of NoSQL databases have been created to support specific needs and use cases. These fall into four main categories of NoSQL systems: Document Databases Document databases, like JSON (JavaScript Object Notation) objects, store data in documents. Each document has a set of field and value pairs. The values might be of many sorts, such as texts, integers, Booleans, arrays, or objects, and their structures are usually aligned with the objects that developers interact with within code. Document databases are useful for a broad number of use cases and may be utilized as a general-purpose database due to their variety of field value types and strong query languages. They can expand out horizontally to accommodate enormous data volumes. Key-Value Databases Key-value databases are a simpler form of database that has keys and values for each item. Learning how to query for a certain key-value pair is usually straightforward because a value ca