1) A good slide show for reference:
http://www.slideshare.net/kgraziano/introduction-to-data-vault-modeling#btnNext
Inmon states that the data warehouse is:
- Subject-oriented
- The data in the data warehouse is organized so that all the data elements relating to the same real-world event or object are linked together.
- Non-volatile
- Data in the data warehouse are never over-written or deleted — once committed, the data are static, read-only, and retained for future reporting.
- Integrated
- The data warehouse contains data from most or all of an organization's operational systems and these data are made consistent.
- Time-variant
- For An operational system, the stored data contains the current value.
Kimball: DW is where we publish used data.
Data Valut by Dan:
Hub: Business Key
Link: represent 3nf many to many relation for Business key
Satellite: description for business key
2)
From:
http://oracledwbi.wordpress.com/2010/03/25/inmon-vs-kimball-architecture-comparison/
Inmon – Hub & Spoke | Kimball – Bus Architecture | |
Methodology & Architecture | ||
Overall approach | Top-down | Bottom-up |
Architectural structure | Enterprise wide (atomic) data warehouse “feeds” departmental databases | Data marts model a single business process; enterprise consistency achieved through data bus and conformed dimensions |
Complexity of the method | Quite complex | Fairly simple |
Comparison with established development methodologies | Derived from the spiral methodology | Four-step process; a departure from RDBMS methods |
Discussion of physical design | Fairly thorough | Fairly light |
Scalability | Growing scope and changing requirements are critical | Need to adapt to highly volatile needs within a limited scope |
Application | Strategic solution | Tactical solution |
Information interdependence | Supported | Supported |
Deployment cost | Higher start-up costs, with lower subsequent project development costs | Lower start-up costs, with each subsequent project costing about the same |
Time to deploy | Longer start-up time | Quick start-up time |
Development skills required | Larger team(s) of specialists | Small teams of generalists |
Persistency of data | High rate of change from source systems | Source systems are relatively stable |
Data modelling | ||
Data orientation | Subject or data-driven | Process oriented |
Tools | Traditional (ERDs, DISs) | Dimensional modelling |
End-user accessibility | Low | High |
Philosophy | ||
Primary audience | IT professionals | End users |
Place in the organisation | Corporate wide facility | Growth subject to departmental demand |
Objective | Deliver a sound technical solution based on proven database methods and technologies | Deliver a solution that makes it easy for end users to directly query the data and still get reasonable response times |
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