Building the Data Warehouse

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With DASD came a new type of system software known as a database management system (DBMS). The purpose of the DBMS was to make it easy for the programmer to store and access data on DASD. In addition, the DBMS took care of such tasks as storing data on DASD, indexing data, and so forth. With DASD and DBMS came a technological solution to the problems of master files. And with the DBMS came the notion of a “database.” In looking at the mess that was created by master files and the masses of redundant data aggregated on them, it is no wonder that in the 1970s a database was defined as a single source of data for all processing.


By the mid-1970s, online transaction processing (OLTP) made even faster access to data possible, opening whole new vistas for business and processing. The computer could now be used for tasks not previously possible, including driving reservations systems, bank teller systems, manufacturing control systems, and the like. Had the world remained in a magnetic-tape-file state, most of the systems that we take for granted today would not have been possible.


PC/4GL Technology


By the 1980s, more new technologies, such as PCs and fourth-generation languages (4GLs), began to surface. The end user began to assume a role previously unfathomed—directly controlling data and systems—a role previously reserved for the data processor. With PCs and 4GL technology came the notion that more could be done with data than simply processing online transactions. MIS (management information systems), as it was called in the early days, could also be implemented. Today known as DSS, MIS was processing used to drive management decisions. Previously, data and technology were used exclusively to drive detailed operational decisions. No single database could serve both operational transaction processing and analytical processing at the same time. Figure 1.1 shows the single-database paradigm.

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