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Data warehouse toolkit notes

Chapter 1

Operational systems turn the wheels of the organisation.

Operational systems perform the same tasks repeatedly, often only updating a single record at a time.

Operational systems will most often reflect the most current state. They typically do not maintain history.

DW/BI - Data Warehouse / Business Intelligence

DW/BI users watch the wheels of the organisation turn to evaluate performance.

DW/BI users evaluate if processes are working correctly and efficiently.

DW/BI systems often need to search across thousands of transactions, that are summarised in an answer set.

DW/BI systems typically demand that historical context be preserved.

Typical DW/BI system requirements include:

The DW/BI system must make information easily accessible

  • contents of DW/BI system must be understandable
  • the data must be intuitive
  • data structures should mimic business users thought processes
  • the BI tools to access data should be simple and easy to use

The DW/BI system must present information consistently

  • data in DW/BI system must be credible
  • data should be cleaned, quality assured
  • data should only be released when fit for user consumption
  • consitent naming and labeling across data sources.

The DW/BI system must adapt to change

  • the DW/BI system must be designed to handle change gracefully.
  • existing data should not be changed or disrupted when the business community asks new questions.
  • If data in DW/BI system does change these changes should be made transparent to users.

The DW/BI system must present information in a timely way

  • Raw data may need to be converted within minutes.

The DW/BI system must be secure

  • Often critical information (eg costs) are in the data warehouse
  • The DW/BI system must effectively control access to this confidential information

The DW/BI system must serve as the authoritative foundation for improved decision making

  • decisions are the most important output form a DW/BI system
  • these decisions are based on analytic evidence
  • you are designing a DECISION SUPPORT SYSTEM

The business community must accept the DW/BI system to deem in successful

  • If the business community does not embrace the DW/BI environment and use it you have failed the acceptance test.
  • DW/BI usage is often optional
  • Business users will adopt DW/BI systems if it is a simple and fast source of information

A DW/BI manager responsibilities

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Dimensional Modeling Introduction

Dimensional modeling is widely accepted as it addresses two main requirements

  1. Deliver dat that's understandable to business users
  2. Deliver fast query performance