Data Warehouse
First thing you should know is :
What is Data Warehouse ?
History of Data Warehousing
v The data warehouse provided the ability to support decision making without disrupting the day-to-day operations, because:
§ Operational information is mainly current – does not include the history for better decision making
§ Issue of quality information
§ Without information history, it is difficult to tell how and why things change over time.
v Data warehouse – a logical collection of information – gathered from many different operational databases – that supports business analysis activities and decision-making tasks
v The primary purpose of a data warehouse is to combined information throughout an organization into a single repository for decision-making purposes – data warehouse support only analytical processing
Data Warehouse Model
v Extraction, transformation, and loading (ETL) – a process that extracts information from internal and external databases,transforms the information using a common set of enterprise definitions, and loads the information into a data warehouse.
v Data warehouse then send subsets of the information to data mart.
v Data mart – contains a subset of data warehouse information
- Relational Database contain information in a series of two-dimensional tables
- In a data warehouse and data mart, information is multidimensional, it contains layers of columns and rows
Dimension – a particular attribute of information
- Cube – common term for the representation of multidimensional information.
- Once a cube of information is created, users can begin to slice and dice the cube to drill down into the information.
v Data mining – the process of analyzing data to extract information not offered by the raw data alone. Also known as "knowledge discovery" – computer-assisted tools and techniques for sifting through and analyzing vast data stores in order to find trends, patterns, and correlations that can guide decision making and increase understanding.
v Information cleansing or scrubbing – a process that weeds out and fixes or discards inconsistent, incorrect, or incomplete information
v Occur during ETL process and second on the information once if is in the data warehouse
Information cleansing activities
Accurate and complete information
v Business intelligence – refers to applications and technologies that are used to gather, provide access, analyze data, and information to support decision making effort.
v these systems will illustrate business intelligence in the areas of customer profiling, customer support, market research, market segmentation, product profitability, statistical analysis, and inventory and distribution analysis to name a few
Eg: Excel, Access
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