Wide-column databases group columns of related data together. Types of nosql databases model and their classification with examples: Wide-Column :This type of databases store data in tables with rows and columns similar to RDBMS, but names and formats of columns can vary from row to row across the table. An app like Facebook can’t be made to work on a straightforward SQL database, except by massive partitioning and sharding, which requires significant adjustments to the app logic as well. The main reason not to use an SQL database is scalability, especially given the write-heavy workloads generated by modern web applications. key-value, wide column, graph, or document are different from those used by default in relational databases, making some operations faster and more flexible sometimes. In an many of the cases, how the use of RDBMSs leads to problems due to fixed schema, which makes them ill-suited for changing business requirements, as schema changes are problematic and time-consuming, causing insufficient performance and latency for the new requirements and limited ability to scale cost-effectively. But what if it is inconvenient to store data in the form of table(s) or we have other kind of relationships between records and want to quickly access the data? The emerging alternative is NoSQL. Relational data can be queried and manipulated by using SQL query language. RDBMSs operate with a relational model defined by schema, where each table is a strictly defined collection of rows and columns and a relationship can then be established between each row in one table and a row in another table. These are called “Not only SQL” for the fact that they may support SQL-like query languages. NoSQL databases are increasingly used in big data and real-time web applications.
A NoSQL originally refers to non-Structured Query Language or non relational database giveing a structure for storing and getting data that is presented in means other than the tabular form or relations likewise used in “relational databases”.Such databases existed from late 90’s, but didn’t obtain the NoSQL brand until a rise of popularity in the early twenty-first century, caused by the needs of Web 2.0 companies such as Yahoo, Facebook, Google, and Amazon. Relational databases are those databases that rely on tables, columns, rows or schemas to organize and retrieve data.
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