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What Is A Data Warehouse? History Current scenario Characteristics Operational Database vs. Data Warehouse Architecture Data Model
Gopal K KGDS
The term "data warehouse" refers to a special type of database that acts as the central repository for company data. It can be thought of as a database archive that is segregated from the operational databases, and used primarily for reporting and data mining purposes.
The relational database revolution in the early 1980s ushered in an era of improved access to the valuable information contained deep within data. Still improvements were needed.
It was soon discovered that databases modeled to be efficient at transactional processing were not always optimized for complex reporting or analytical needs
Inmon champions the large centralized Data Warehouse approach leveraging solid relational design principles. His Corporate Information Factory remains an example of this "top down" philosophy.
Kimball, on the other hand, favors the development of individual data marts at the departmental level that get integrated together using the Information Bus architecture. This "bottom up" approach dovetails nicely with Kimball's preference for star-schema modeling
Many of the current changes in today's data industry also affect Data Warehousing. Cloud storage and high-velocity, real-time data analysis being two obvious factors playing a role in the practice's evolution. On the end-user side, web-based and mobile access to decision support or reporting data is a major requirement on many projects. Advances in the practice of ontology have enhanced the capabilities of ETL systems to parse information out of unstructured as well as structured data sources
Subject-orientedThe data in the database is organized so that all the data elements relating to the same real-world event or object are linked together.
Time-variantThe changes to the data in the database are tracked and recorded so that reports can be produced showing changes over time.
Non-volatileData in the database is never over-written or deleted. Once committed, the data is static, read-only, but retained for future reporting.
IntegratedThe database contains data from most or all of an organization's operational applications, and that this data is made consistent.
The processing load of reporting reduced the response time of the operational systems.
The database designs of operational systems were not optimized for information analysis and reporting.
Most organizations had more than one operational system, so company-wide reporting could not be supported from a single system.
Development of reports in operational systems often required writing specific computer programs which was slow and expensive.
Consolidation of data from a wide variety of data sources.
Ability to analyze data beyond the level of standard monitoring reports.
Operational response time unaffected.
