Data warehouse fundamentals
Ø Data warehouse – A logical collection of information – gathered from many different operational databases – that supports business analysis activities and decision-making takes
Ø 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
Ø 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.
Ø Data warehouse then send subsets of the information to data mart.
Ø Data mart – contains a subset of data warehouse information.
Multidimensional Analysis and Data Mining
Ø Relational Database contains information in a series of two-dimensional tables.
Ø 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.
Ø Users can analyze information in a number of different ways and with number of different dimensions.
Ø 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 finds trends, patterns and correlations that can guide
decision making and increase understanding
Ø To perform data mining users need data-mining tools
- Data-mining tool – uses a variety of techniques to finds patterns and relationships in large volumes of information. Eg: retailers and use knowledge of these patterns to improve the placement of items in the layout of a mail-order catalog page or Web page.
Information Cleansing or Scrubbing
Ø An organization must maintain high-quality data in the data warehouse
Ø Information cleansing or scrubbing – A process that weeds out and fixes or discards inconsistent, incorrect or incomplete information
Ø Occurs during ETL process and second on the information once if is in the data warehouse
Ø Contract information in an operational system
Ø Standardizing Customer name from Operational Systems
Ø Information cleansing activities
- Missing Records or Attributes
- Redundant Records
- Missing Keys or Other Required Data
- Erroneous Relationships or References
- Inaccurate Data
Accurate and complete information
Business Intelligence
Ø Business Intelligence – refers to applications and technologies that are used to gather, provides access, analyze data and information to support decision making efforts
Ø 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
Ø Eg; Excel, Access
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