Data Warehouse concept need and history

Introduction and Need

Today in the age of information technology data is an important entity. Today many companies face the problem related to data like

o   Data is scattered over the network

o   Many versions, subtle differences

o   Need an expert to get the data

o   Available data poorly documented

o   Data found can’t be used

§  Results are unexpected

§  Data needs to be transformed from one form to other

So data warehouse concept was introduced to tackle such problems.

Definitions

A warehouse is a subject oriented, integrated, time variant and non volatile collection of data in support of management’s decision making process.

Data warehouse is defined as a single, complete and consistent store of data obtained from a variety of different sources made available to end users in what they can understand and use in a business context.

Data Warehouse is combining data from multiple sources in one comprehensive database. It is a process of transforming data into information and making it available to users in a timely enough manner to make a difference.

Data warehouse is a technique for assembling and managing data from various sources for the purpose of answering business questions thus making decisions that were not previous possible.

It is a decision support database maintained separately from the organization’s operational database.

Characteristics

Data warehouse has following characteristics

• Subject oriented – Data that gives information about a particular subject instead of about the company’s ongoing operations.

• Integrated – Data that is gathered into data warehouse from a variety of sources and merged into a coherent whole.

• Time variant – All data in data warehouse is identified with a particular time period.

• Non volatile – Data is stable in data warehouse. More data is added but data is never removed.

History

The Key developments in early years of data warehousing are

• 1960 – General Mills and Datrmouth College in joint research project.
• 1970 – ACNielson and IRI provide dimensional data marts for retail sales.
• 1983 – Teradata introduces a database management sys specifically designed for decision support .
• 1988 – Barry Devlin & Paul murphy published the article An architecture for a business & info. Sys  In IBM systems Journal where they introduced the term “Business data warehouse”
• 1990 – Red Brick systems introduces Red Brick Warehouse a database mang sys. for data warehousing.
• 1991 – Prism solutions intorduced Prism Warehouse manager s/w for developing a warehouse.
• 1995 – The data warehousing institute that promotes data warehousing is founded
• 1996 – Ralph kimball publishes the book The Data Warehouse Toolkit
• 1997 – Oracle 8 with support for star queries is released.

Uses

• Analyse trends – Data warehouse is commonly used by the companies to analyse trends over time.
• View operations – Companies can use the data warehouse to view day to day operations.
• Planning – Its main purpose however is to facilitate the strategic planning resulting from long term data overviews.
• Other uses – The overview can be used to
• Build the business model,
• Make forecasts,
• Write reports etc.
• Current data – Data warehouse is used to make up to date database.