Relational databases are databases that rely on tables, columns, rows, or schemas to organize and retrieve data. A NoSQL originally refers to an unstructured query language or non-relational database giving a structure for storing and obtaining data presented in a form other than the tabular form or relationships also used in "databases". relational data”. Such databases had existed since the late 1990s, but only gained the NoSQL brand with increasing popularity in the early 21st century, brought about by the needs of Web 2.0 companies such as Yahoo, Facebook, Google and Amazon. NoSQL databases are increasingly used in Big Data and real-time web applications. These are called "Not Just SQL" because they can support SQL-like query languages. Say no to plagiarism. Get Custom Essay on “Why Violent Video Games Should Not Be Banned”?Get the original essayWhy the need for NoSQL?RDBMS work with a schema-defined relational model, where each table is a strictly defined collection of rows and columns and a relationship can then be established between each row of a table and a row of another table. Relational data can be queried and manipulated using the SQL query language. But what if it is not practical to store data as a table(s) or we have other types of relationships between records and we want to access the data quickly? The emerging alternative is NoSQL. In many cases, how the use of RDBMS results in problems due to a fixed schema, making them ill-suited to changing business requirements, as schema changes are problematic and time consuming, resulting in poor performance and insufficient latency for new requirements. and limited ability to scale profitably. The data structures used, for example key-value, wide column, chart or document, are different from those used by default in relational databases, making some operations faster and sometimes more flexible. The main reason not to use an SQL database is scalability, especially given the write-heavy workloads generated by modern web applications. An application like Facebook cannot run on a simple SQL database except through massive sharding and sharding, which also requires significant adjustments to the application logic. This is why Facebook developed Cassandra. Types of nosql database models and their classification with examples: Wide-Column: This type of databases stores data in tables with rows and columns similar to RDBMS, but the column names and formats may vary. vary from one row to another in the table. Wide column databases group related columns of data together. For example Accumulo, Cassandra, Druid, HBase, Vertica.Document: This type of databases usually stores self-describing JSON, XML and BSON documents. For example, Apache CouchDB, ArangoDB, BaseX, Clusterpoint, Couchbase, Cosmos DB, IBM Domino, MarkLogic, MongoDB, OrientDB, Qizx, RethinkDBKey-value: This type of databases emphasizes simplicity and is very useful for speed up an application to support high-speed playback. and non-transactional data write processing. For example Aerospike, Apache Ignite, ArangoDB, Couchbase, Dynamo, FairCom c-treeACE, FoundationDB, InfinityDB, MemcacheDB, MUMPS, Oracle.