<P> Document - oriented database Clusterpoint uses inverted indexing model to provide fast full - text search for XML or JSON data objects for example . </P> <P> The relational model was introduced by E.F. Codd in 1970 as a way to make database management systems more independent of any particular application . It is a mathematical model defined in terms of predicate logic and set theory, and its implementing it have been used by mainframe, midrange and microcomputer systems . </P> <P> The products that are generally referred to as relational databases in fact implement a model that is only an approximation to the mathematical model defined by Codd . Three key terms are used extensively in relational database models: relations, attributes, and domains . A relation is a table with columns and rows . The named columns of the relation are called attributes, and the domain is the set of values the attributes are allowed to take . </P> <P> The basic data structure of the relational model is the table, where information about a particular entity (say, an employee) is represented in rows (also called tuples) and columns . Thus, the "relation" in "relational database" refers to the various tables in the database; a relation is a set of tuples . The columns enumerate the various attributes of the entity (the employee's name, address or phone number, for example), and a row is an actual instance of the entity (a specific employee) that is represented by the relation . As a result, each tuple of the employee table represents various attributes of a single employee . </P>

Explain the customer database model and their advantages and disadvantages