Using sequential media for storage meant the entire file had to be accessed, even if only
a fraction of the file was needed. Oxide often stripped off of magnetic tapes, and entire
files were lost. These issues led to the need for a new way to analyze information.
Early Data Processing Applications:
With sequential storage, data was organized onto what was called a master file, which held central information that was useful to many applications. Punch cards, magnetic tapes, and reports were generated from the applications, but were soon replaced by disk storage. With disk storage, data could be accessed directly and efficiently. Processors grew more powerful and versatile, and the speed and costs of processing dropped dramatically. As data was stored onto disk, master files mutated into databases. This techniques are used in data ware housing models. Here i would like to give a short information about data warehousing techniques.
Since the beginning of movement toward data warehousing, data warehouses have
been defined as being:
Subject-oriented. Data is organized around a major object or process of an organization. Classic examples include subject area databases for customer, material, vendor, and transaction.
Integrated. The data from various subject areas should be rationalized with one another.
Nonvolatile. Data in a data warehouse is not updated. Once a record is properly
placed in the warehouse, it is not subject to change.