(c) Columnar databases
Columnar databases are a hybrid between NoSQL and relational databases. They provide some row-and-column structure, but do not have the strict rules of relational databases. Column-oriented databases store and process data by column instead of row. Having its origin in analytics and business intelligence, column-stores can be used to build high-performance applications. Column oriented [6] stores are seen less puristic, subsuming data stores that integrate column and roworientation. This is faster because most of the tables contain lots of columns which are rarely used simultaneously by queries. Columnar databases only perform I/O on the blocks corresponding to columns that are actually being read/updated. In addition to the smaller I/O overhead, memory is more efficiently utilized. The column-oriented data store very effective in blocking data based on each column’s data type such as Date, Text,etc.