Relational database models handle data tables that have a prior interlinking connection or relationship. Non-relational databases came into the picture when the data needs of the business world were not limited to a few indexed databases.
For example, if a particular database of a few thousand tables needs to be queried, relational databases such as Microsoft SQL Server or MySQL can be very helpful in handling the related transactions. But if a transaction or data query needs millions of unrelated web pages to be crawled, non-relational databases such as Hadoop file systems or NoSQL will be needed.
Relational vs. non-relational databases
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