The design and development of typical systems often use data management and relational databases as key building blocks. Advanced queries expressed in SQL work well with the strict relationships imposed by relational databases. However, relational database technology was not originally designed for use over distributed systems. This limitation has been addressed through clustering enhancements, although some fundamental operations—such as
data synchronization—still require complex and expensive protocols. Modern relational databases can exhibit poor performance on data-intensive systems. As a result, the
NoSQL paradigm has been adopted within database management systems for cloud-based systems. NoSQL storage does not require fixed table schemas, and join operations are typically avoided. NoSQL databases have been shown to provide efficient horizontal scalability, high performance, and ease of integration into cloud applications. Additionally, data models that rely on simplified relay algorithms have been employed in data-intensive cloud mapping applications specific to virtual frameworks. It is also important to differentiate between cloud databases which are relational (SQL) and those that are non-relational (NoSQL). ; SQL databases: SQL databases can run in the cloud either on virtual machines or as a managed service, depending on the vendor. While SQL databases are generally easy to scale vertically, horizontal scalability presents a greater challenge. ; ; NoSQL databases: NoSQL databases are designed to service heavy read/write loads and can scale up and down easily,{{cite journal|author = Agrawal, Rakesh |title = The Claremont report on database research |journal = SIGMOD Record |volume = 37 |number = 3 |year = 2008 |issn = 0163-5808 |pages = 9–19 |doi = 10.1145/1462571.1462573 |url= http://db.cs.berkeley.edu/claremont/claremontreport08.pdf : : Some SQL databases have developed NoSQL capabilities, including
JSON, binary JSON (e.g.
BSON or similar variants), and key-value store data types. : : Multi-model databases combine relational and non-relational capabilities, providing a standard SQL interface to users and applications. Native multi-model databases support multiple data models with a single core, facilitating their use in applications built around SQL. == Vendors ==