
Introducing Big Data | 29
Indeed, one should write SQL queries for them. Also, unlike MapReduce, there is no Reduce
step, although the queries can always do aggregational work. Even though they are really a grid
of multiple databases, they present an interface where one sends them a single query and one
gets back a single result set. Thus, it abstracts the complexity of parallel processing. Typically,
MPP data warehouses are packaged as physical appliances, and typically, they do not use direct
attached storage, but instead they use a more enterprise-oriented network storage scheme.
2.7.5 NoSQL
NoSQL stands for ‘not only SQL’. NoSQL databases ...