Data Warehousing and Data Mining By N.Gopinath AP/CSE For ppt and Notes refer : http://dwdmbygopi.weebly.com/index.html

Learning Objective Understand the basic definitions and concepts of data warehouses Describe data warehouse architectures (high level). Describe the processes used in developing and managing data warehouses Explain data warehousing operations Explain the role of data warehouses in decision support

Contd… Explain data integration and the extraction, transformation, and load (ETL) processes Describe real-time (active) data warehousing Understand data warehouse administration and security issues

Data warehousing definition Data warehousing is a Subject oriented, integrated, time variant and non-volatile collection of data in support of management’s decision making process.

Contd… Subject Oriented: Data that gives information about a particular subject instead of about a company's ongoing operations. Integrated: Data that is gathered into the data warehouse from a variety of sources and merged into a coherent whole. Time-variant: All data in the data warehouse is identified with a particular time period. Non-volatile: Data is stable in a data warehouse. More data is added but data is never removed.

Characteristics of data warehousing Subject oriented Integrated Time variant (time series) Nonvolatile Web based Relational/multidimensional Client/server Real-time Include metadata

Some definitions and Concepts Data mart A departmental data warehouse that stores only relevant data Dependent data mart A subset that is created directly from a data warehouse Independent data mart A small data warehouse designed for a strategic business unit or a department

Contd… Operational data stores (ODS) A type of database often used as an interim (Used for a particular period of time) area for a data warehouse, especially for customer information files Enterprise data warehouse (EDW) A technology that provides a vehicle for pushing data from source systems into a data warehouse Metadata Data about data. In a data warehouse, metadata describe the contents of a data warehouse and the manner of its use

Data warehousing process overview Organizations continuously collect data, information, and knowledge at an increasingly accelerated rate and store them in computerized systems The number of users needing to access the information continues to increase as a result of improved reliability and availability of network access, especially the Internet

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