Siksha Sarovar

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Siksha Sarovar is a free e-learning platform for coding courses, BCA university notes and competitive exam preparation. Optional Google sign-in saves your learning progress across devices.

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Definition of a Data Warehouse

Lesson 2 of 32 in the free Data Warehousing and Data Mining(Elective-II) notes on Siksha Sarovar, written by Rohit Jangra.

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2. Definition of a Data Warehouse

2.1 The Inmon Definition

William H. Inmon, widely recognized as the "Father of Data Warehousing," provided the most accepted definition. He defines a Data Warehouse as a subject-oriented, integrated, time-variant, and non-volatile collection of data in support of management's decision-making process.

2.2 Deep Dive into Characteristics

CharacteristicDefinitionExplanation
Subject-OrientedData is organized around major subjects rather than specific business applications.Operational DB: Organized by applications (Order Processing App, Loan App). <br> Data Warehouse: Organized by subjects (Customer, Product, Sales, Vendor). It focuses on modeling and analysis of data.
IntegratedData from different sources is stored in a consistent format.Integration involves resolving conflicts in naming conventions, units of measure, and encoding schemes. E.g., Gender: 'M/F', '1/0', 'Male/Female' becomes uniform.
Time-VariantData is associated with a specific point in time.A DW provides a historical perspective. It contains time-series data (daily, weekly, monthly) rather than just current status. Every record has a timestamp or time-key.
Non-VolatileOnce data is entered into the warehouse, it is not updated or deleted.Operational data changes constantly. Warehouse data is loaded (usually nightly) and then used for reading. No transaction processing happens here. It provides a stable view of history.