Clase2 introdw
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Transcript of Clase2 introdw
Data sources often store only current data, not historical data
Corporate decision making requires a unified view of all organizational data, including historical data
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Data warehouse A physical repository where relational data are
specially organized to provide enterprise-wide, cleansed data in a standardized format
A DW delivers a collection of integrated data used to support the decision making process for the enterprise
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A data warehouse is a repository (archive) of information gathered from multiple sources, stored under a unified schema, at a single site
Greatly simplifies querying, permits study of historical trends
Shifts decision support query load away from transaction processing systems
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Characteristics of data warehousing Subject oriented ▪ organized based on use: sales, products, customers
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Characteristics of data warehousing Integrated ▪ inconsistencies removed
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Characteristics of data warehousing Time variant: data are normally time series, A
warehouse maintains historical data
Nonvolatile: stored in read-only format, periodically refreshed, Changes are recorded as new data
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Characteristics of data warehousing Summarized ▪ in decision-usable format
Large volume ▪ data sets are quite large
Non normalized ▪ often redundant
Metadata ▪ data about data are stored
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Integrated, company-wide view of high-quality information (from disparate databases)
Separation of operational and informational systems and data (for improved performance)
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Data mart A departmental data warehouse that stores
only relevant data Focuses on a particular subject or department
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Organizational
Data
Warehouse
Finance
Data Mart
Accountin
g
Data Mart
Marketing
Data Mart
Sales
Data Mart
Operational
Data Store
Operational
Data Store
Operational
Data Store
Operational
Data Store
Legacy
Systems
Legacy
systems
feed data to
the
warehouse.
The
warehouse
feeds
specialized
information to
departments. 12
Organizational
Data
Warehouse
Finance
Data Mart
Accting
Data Mart
Marketing
Data Mart
Sales
Data Mart
Data Marts
Departmentalized
Summarized, aggregated
data
Star join design
Limited historical data
Limited data volume
Requirements driven data
Focused on departmental
needs
Multi-dimensional DBMS
technologies
Organizational Data
Warehouse
Corporate
Highly granular data
Normalized design
Robust historical data
Large data volume
Data Model driven data
Versatile
General purpose DBMS
technologies
The data
mart serves
the needs of
one
business
unit, not the
organization.
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Dependent data mart A subset that is created directly from a data
warehouse Quality data
Support enterprise wide data model
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Independent data mart A small data warehouse designed for a
strategic business unit or a department, but its source is not an EDW
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Operational data stores (ODS) A type of database often used as an interim
area for a data warehouse, especially for customer information files
Volatile Used for short-term decisions involving
mission-critical application
Store only very recent information
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Oper marts An operational data mart. An oper mart is a
small-scale data mart typically used by a single department or functional area in an organization
The data for an oper-mart come from an ODS
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Enterprise data warehouse (EDW)
Is a large scale DW that is used across the enterprise for decision support
A technology that provides a vehicle for pushing data from source systems into a data warehouse
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Metadata Data about data. In a data warehouse,
metadata describe the contents of a data warehouse and the manner of its use
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Metadata
As with other databases, a warehouse must include a metadata repository
▪ Information about physical and logical organization of data
▪ Information about the source of each data item and the dates on which it was loaded and refreshed
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Direct benefits of a data warehouse
Allows end users to perform extensive analysis
Allows a consolidated view of corporate data
Better and more timely information
Enhanced system performance
Simplification of data access
Data integration
No more redundancy
Consistency of data content
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Direct benefits of a data warehouse
Improved data quality
Historical enterprise data
Unlimited, ad-hoc reporting
Reliable trend analysis reporting
Faster data delivery and data access
Business intelligence (BI) capabilities
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Indirect benefits result from end users using these direct benefits
Enhance business knowledge
Present competitive advantage
Enhance customer service and satisfaction
Facilitate decision making
Help in reforming business processes
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DECISION SUPPORT SYSTEMS AND BUSINESS INTELLIGENCE. Turban
Modern Data Warehousing, Mining, and Visualization: Core Concepts. George M. Marakas
Modern Database Management.9th Edition.Jeffrey A. Hoffer, Mary B. Prescott, Heikki Topi
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