Editing Database (section)

===2000s, NoSQL and NewSQL===
{{Main|NoSQL|NewSQL}}

[[XML database]]s are a type of structured document-oriented database that allows querying based on [[XML]] document attributes. XML databases are mostly used in applications where the data is conveniently viewed as a collection of documents, with a structure that can vary from the very flexible to the highly rigid: examples include scientific articles, patents, tax filings, and personnel records.

[[NoSQL]] databases are often very fast, do not require fixed table schemas, avoid join operations by storing [[denormalization|denormalized]] data, and are designed to [[horizontal scaling|scale horizontally]].

In recent years, there has been a strong demand for massively distributed databases with high partition tolerance, but according to the [[CAP theorem]], it is impossible for a [[distributed computing|distributed system]] to simultaneously provide [[consistency model|consistency]], availability, and partition tolerance guarantees. A distributed system can satisfy any two of these guarantees at the same time, but not all three. For that reason, many NoSQL databases are using what is called [[eventual consistency]] to provide both availability and partition tolerance guarantees with a reduced level of data consistency.

[[NewSQL]] is a class of modern relational databases that aims to provide the same scalable performance of NoSQL systems for online transaction processing (read-write) workloads while still using SQL and maintaining the [[ACID (computer science)|ACID]] guarantees of a traditional database system.