To store and process large volumes of data more efficiently, methods have been developed to minimize disk space and data redundancy, and to increase processing speed. Most databases store information in hierarchical or relational structures rather than as flat files because they are more efficient for storing information.
Hierarchical databases group records in such a way that their relationships form a tree-like structure. They are well suited for organizing information that is structured into successively greater levels of detail, and allow rapid access to the information that is accessed most frequently. Individual records are not necessarily contained in the same file.
Relational databases save space by storing common information in one table, and detail information in other related tables. A request for information from the database returns a table-like View that contains information assembled on demand from related fields in related tables in the database.
The relationships between different types of information in a database can be complex, and the information can change frequently. Database systems can generate reports that display selected information at a given moment. Whether printed or electronic, report (print image) files are always flat, two-dimensional representations of selected data relationships.
Analyzer can also use report files as the basis for an analysis. Report files are often available when the data in its original form is not. Sometimes it is not feasible to obtain data from a relational database in a flat file format. If you can obtain a report file of the data you need, you have, in effect, a flat, sequential file that you can use.