Chapter 1

Introduction

In today's world, Information about the market at photon's speed helps the Industry to make strategic decisions proving Darwin's theory, Survival of the fittest. Making right decision at the right time helps the wheel of Industry to pass through hurdles. Data warehousing is Industry's heart for strategc decision making.

A data warehouse is core repository of the organization's historical data, or called community memory. It is the data, information and the knowledge used by people for interacting using these object in making decisions. For example, an organization would use the information that's stored in its data warehouse to find out what day of the week they sold the most Widgets in May 1992, or how employee sick leave the week before Christmas differed between Mumbai and Seattle from 2002 - 2006. In other words, the data warehouse contains the raw material for management's DSS(decision support system). The critical factor leading to the use of a data warehouse is that a data analyst can perform complex queries and analysis (such as data mining) on the information without slowing down the operational systems.

Origin/History of Data Warehouse

During the late 80s to Early 90s Data Warehouses became a unique type of computer database . The sole purpose to develop is to meet a growing demand for management information and analysis that could not be met by operational systems. Operational systems were unable to meet this need for a range of reasons:

• The processing load of reporting reduced the response time of the operational systems,
• The database designs of operational systems were not optimized for information analysis and reporting,
• Most organizations had more than one operational system, so company-wide reporting could not be supported from a single system, and
• Development of reports in operational systems often required writing specific computer programs which was slow and expensive

As a result, separate computer databases began to be built that were specifically designed to support management information and analysis purposes. These data warehouses were able to bring in data from a range of different data sources, such as mainframe computers, minicomputers, as well as personal computers and office automation software such as spreadsheet, and integrate this information in a single place. This capability, coupled with user-friendly reporting tools and freedom from operational impacts, has led to a growth of this type of computer system.

Advantages of using data warehouse

There are many advantages to using a data warehouse, some of them are:

• Enhances end-user access to a wide variety of data.
• Business decision makers can obtain various kinds of trend reports e.g. the item with the most sales in a particular area / country for the last two years.

A data warehouse can be a significant enabler of commercial business applications, most notably customer relationship management (CRM) the automation or support of customer processes involving sales or service representatives.

Concerns in using data warehouses

• Extracting, cleaning and loading data is time consuming.
• Data warehousing project scope must be actively managed to deliver a release of defined content and value.
• Problems with compatibility with systems already in place.
• Security could develop into a serious issue, especially if the data warehouse is web accessible.
• Data Storage design controversy warrants careful consideration and perhaps prototyping of the data warehouse solution for each project's environments