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DBpedia 2015-10

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Matches in DBpedia 2015-10 for { ?s ?p "A NoSQL (originally referring to "non SQL" or "non relational" ) database provides a mechanism for storage and retrieval of data that is modeled in means other than the tabular relations used in relational databases. Such databases have existed since the late 1960s, but did not obtain the "NoSQL" moniker until a surge of popularity in the early twenty-first century, triggered by the needs of Web 2.0 companies such as Facebook, Google and Amazon.com.Motivations for this approach include: simplicity of design, simpler "horizontal" scaling to clusters of machines, which is a problem for relational databases, and finer control over availability. The data structures used by NoSQL databases (e.g. key-value, graph, or document) differ slightly from those used by default in relational databases, making some operations faster in NoSQL and others faster in relational databases. The particular suitability of a given NoSQL database depends on the problem it must solve. Sometimes the data structures used by noSQL databases are also viewed as "more flexible" than relational database tables.NoSQL databases are increasingly used in big data and real-time web applications. NoSQL systems are also sometimes called "Not only SQL" to emphasize that they may support SQL-like query languages.Many NoSQL stores compromise consistency (in the sense of the CAP theorem) in favor of availability, partition tolerance, and speed. Barriers to the greater adoption of NoSQL stores include the use of low-level query languages (instead of SQL, for instance the lack of ability to perform ad-hoc JOIN's across tables), lack of standardized interfaces, and huge previous investments in existing relational databases.Most NoSQL stores lack true ACID transactions, although a few recent systems, such as FairCom c-treeACE, Google Spanner (though technically a NewSQL database), FoundationDB, Symas LMDB and OrientDB have made them central to their designs. (See ACID and JOIN Support.) Instead they offer a concept of "eventual consistency" in which database changes are propagated to all nodes "eventually" (typically within milliseconds) so queries for data might not return updated data immediately.Not all NoSQL systems live up to the promised "eventual consistency" and partition tolerance, but in experiments with network partitioning often exhibited lost writes and other forms of data loss. Fortunately, some NoSQL systems provide concepts such as "Write Ahead Logging" to avoid data loss. Current relational databases also "do not allow referential integrity constraints to span databases" as well."@en }

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